Based bionic principle, this paper built a multi-phase central pattern generator model capable of producing multiply bionic gaits. This model could realize the arbitrary adjusting and transforming between different movement types of snake robots by introducing external excitatory, which will be helpful to improve the environments adaptability of snake robots. In this paper, the stability of arbitrary segments multi-phase central pattern generator was proved. The influence of multi-phase central pattern generator model parameters to system outputs was analyzed. For conclude the optimization strategy of multi-phase central pattern generator outputs amplitude, the relationship between optimal amplitude of snake robots and environments parameters in serpentine locomotion. Constrains between model parameters and external excitatory were built, which enabled snake robots controlled by multi-phase central pattern generator to move in three dimensional space and adapt to environments. Finally, the validity of this bionic control method and the similarity of snake gaits were verified with the snake robot platform.