13. A non-transitory computer usable medium having computer readable program instructions embodied therein for causing a computer to perform: traversing a flowchart, wherein said flowchart comprises a main processing flow, a logic structure within said main processing flow, and a processing activity in said logic structure; forming an equivalent tree diagram corresponding to the main processing flow of the flowchart; transforming the logic structure in the flowchart to a sub tree comprising a branching node in the equivalent tree diagram; assembling the sub tree to the equivalent tree diagram; transforming a task required by the processing activity to a leaf node below the branching node in the sub tree; and decomposing the task represented by the leaf node to a least one sub task and setting each sub task as a child leaf node below the leaf node; modifying the leaf node to a sub-branching node of a type corresponding to an execution logic of the at least one sub task, wherein the execution logic comprises a loop logic structure and at least one of: a sequence logic structure and a split logic structure; repeating the decomposing and modifying steps until the tasks represented by all the leaf nodes in the equivalent tree diagram cannot be further decomposed; and selecting at least one node in the flowchart for editing; executing the editing of the selected node; using a reorganization verifying unit for verifying validity of the editing, comprising: determining that the editing is valid when the at least one node corresponds to a sub tree in the equivalent tree diagram; and determining that the editing is valid when the at least one node corresponds to a plurality of sub trees in the equivalent tree diagram and said plurality of sub trees have a same parent node in common.
13. A non-transitory computer usable medium having computer readable program instructions embodied therein for causing a computer to perform: traversing a flowchart, wherein said flowchart comprises a main processing flow, a logic structure within said main processing flow, and a processing activity in said logic structure; forming an equivalent tree diagram corresponding to the main processing flow of the flowchart; transforming the logic structure in the flowchart to a sub tree comprising a branching node in the equivalent tree diagram; assembling the sub tree to the equivalent tree diagram; transforming a task required by the processing activity to a leaf node below the branching node in the sub tree; and decomposing the task represented by the leaf node to a least one sub task and setting each sub task as a child leaf node below the leaf node; modifying the leaf node to a sub-branching node of a type corresponding to an execution logic of the at least one sub task, wherein the execution logic comprises a loop logic structure and at least one of: a sequence logic structure and a split logic structure; repeating the decomposing and modifying steps until the tasks represented by all the leaf nodes in the equivalent tree diagram cannot be further decomposed; and selecting at least one node in the flowchart for editing; executing the editing of the selected node; using a reorganization verifying unit for verifying validity of the editing, comprising: determining that the editing is valid when the at least one node corresponds to a sub tree in the equivalent tree diagram; and determining that the editing is valid when the at least one node corresponds to a plurality of sub trees in the equivalent tree diagram and said plurality of sub trees have a same parent node in common. 19. The computer usable medium of claim 13 wherein the computer readable program instructions further cause the computer to modify the flowchart by performing: initializing a modified flowchart to comprise a begin node and an end node; setting a position between the begin and end nodes as a current position in the modified flowchart; setting the root node of the modified equivalent tree diagram as a current node in the modified flowchart; performing iteratively, while traversing the modified equivalent tree diagram, beginning with the current node until the current node equals a null node: fetching a next node in the equivalent tree diagram as the current node in depth first traversal; performing iteratively until the current node is not a leaf node: inserting a processing activity node corresponding to the current node into the current position; and moving the current position to a next insert position in that logic structure; generating a corresponding logic structure according to the execution type of the current node; inserting the logic structure into the current position; and moving the current position to the first insert position in said logic structure.