File decryption method for Android system

The invention relates to the technical field of file decryption, and discloses a file decryption method for an Android system, which comprises the following steps of: S1, uploading a file: uploading an apk file which needs to be decrypted on an Android mobile phone side to a computer side; s2, decompiling the file: right-clicking the apk and opening the apk in a decompiling tool mode to obtain a folder; s3, opening the file; s4, querying the file; s5, modifying the file; s6, determining a signature value; s7, copying the signature value; s8, determining a secret key; s9, decrypting the file; according to the method, the decryption of the software file in the Android system can be conveniently completed, and a user can conveniently modify a code according to requirements, so that different software use feelings are obtained; and in the decryption process of the feature extraction software, the signature value required by decryption is automatically obtained through a preprocessing unit, an extraction unit, a c