The stable walking pattern plays an important role in the control of biped robot.This research proposes a three-dimensional linear inverted pendulum model of walking robot. Through the three-dimensional inverted pendulum, the location of center of mass and speed of the robot can be calculated, combined with the robot's inverse kinematics, the angle of each joint of robot can be obtained. Then, these angles can be used to drive the movement of each joint of robot. At last, the complete trajectory of robot can be obtained.