1. A method for register clearing in data flow analysis in decompilation, comprising: opening a code file in assembly language before the register clearing, and reading all function statements in the code file; performing judgment on each of the read function statements sequentially to judge whether the function statement comprises a register name, and in a case that the function statement comprises the register name, creating a binary tree and inputting the function statement into the binary tree; and performing judgment on each of the function statements comprising the register name sequentially to judge whether the function statement comprises a right child end tag of the binary tree, and in a case that the function statement comprises the right child end tag of the binary tree, performing an elimination process on the created binary tree to remove the register name from the binary tree, to generate a simplest binary tree, and generating a function statement in high-level language based on the simplest binary tree; and in a case that the function statement comprises no right child end tag of the binary tree, judging whether a next function statement comprises a register name.