The invention discloses an implementation method of an SM4-like cryptographic algorithm, which belongs to the technical field of cryptography. The method comprises the following steps of: grouping file data to be encrypted to generate a plurality of pieces of data, and dividing the plurality of pieces of data into a first type of input data and a second type of input data; performing cyclic shiftoperation on at least two branch data in the first type of input data to obtain preprocessed first type of input data; performing first exclusive-OR operation on the preprocessed first type of input data, and sequentially inputting the first type of input data into an S box for change and P replacement to obtain first output data; and performing a second XOR operation on the first output data andthe second type of input data to obtain an intermediate state, and performing iteration on the intermediate state to obtain a ciphertext. The cyclic shift operation is introduced before XOR of the first type of input data, so that the relative positions of the same data entering the S box for three times are different, and the diffusivity of the algorithm is improved.