This paper proposes the redundancy trajectory generation method for biped robots. First of all, the position and orientation variables of a robot's foot and body are chosen as the reference factors. And the augmented Jacobian method is used at the acceleration level with the differential equation of reference factors and ZMP equation to guarantee the minimum motion factor and the stability condition. The virtual spring-damper system is reflected as an additional task at the null-space component to make a symmetrical walking motion. To prove the effectiveness of the proposed the redundancy trajectory generation method, computer simulations are carried out.