The invention discloses a white box block cipher construction method and system based on a FeistelBox structure. The method comprises: inputting n-bit plaintext, setting a block size n a , the number of iterative processing rounds r of the FeistelBox structure, use the T function to perform bit conversion, and convert the input n a bit bit to n b bit bit output, where n a +n b =n; add affine transformation between the rounds of the iterative processing rounds, and perform chain connection, the operation of each round is closely connected with the operation of the previous round and the next round, by converting the affine of the previous round The inverse transformation of the transformation is embedded in the lookup table operation of this round, and then the affine transformation of the previous round is applied to the result of the lookup table, and the affine transformation layer adopts the reversible affine transformation matrix; the encryption operation of S1-S2 is performed to obtain Encryption result; the system includes a bit conversion module, an affine transformation module and an execution operation module. The invention makes it impossible for the attacker to obtain the information of the ciphertext, increases the difficulty for the attacker to crack the password, and strengthens the security of key storage.