1. A method for detecting hidden information embedded in a document comprising characters, wherein, a document for detection is formed by embedding hidden information in an original document by performing layout transformation on characters in the original document according to a predetermined embedding rule, and the method comprises: determining layout transformation for each character in the document for detection compared with the original document; obtaining a code sequence embedded in the document for detection based on the layout transformation of each character in the document for detection and the predetermined embedding rule; decoding the code sequence to get the hidden information embedded in the document for detection; wherein, the predetermined embedding rule comprises: acquiring a code sequence for each class of layout transformation by coding the hidden information to be embedded in the class of layout transformation; wherein, each class of layout transformation is considered as a channel to embed the hidden information; selecting the characters to be subjected to the layout transformation for each class of the layout transformation from the document respectively, length of the characters to be subjected to the layout transformation being larger than or equal to length of the code sequence corresponding to each class of the layout transformation; performing the layout transformation on the selected characters according to the acquired code sequence for each class of the layout transformation in a cyclic application, each value in the code sequence for each class of the layout transformation corresponding to a transformation number of each class of the layout transformation.