Abstract: This paper studies on the serpent encryption algorithms for differential features, and it takes advantage of constructing differential-algebraic equations method of s-box . A Eight-rounds of dlfferential-algebralc attack methods of Serpent-128. The method of eight-round serpent-128 need for selective plaintext pairs of 2 ×2⁹⁵ ×2¹⁴= 2¹¹⁰ ,2⁹⁶ eight rounds of encryption and decryption of 2⁹⁶, Memory storage space for grouping 2¹¹⁰, To guess 8 round serpent-128 12-bit encryption keys.