The invention provides a walking motion planning method for a biped walking robot. The walking motion planning method takes an omnidirectional moving trolley as a model, takes a condition that the trolley does not overturn as a dynamics constraint condition, considers the dynamics constraints in footprint transform, uses a three-dimensional linear inverted pendulum model between partial discrete footprints, generates a hip trajectory online, and obtains driving joint trajectories through inverse kinematics; and finally, the walking motion planning method adopts a multi-rigid-body dynamics model, adopts a ZMP theory to determine stability, verifies the effectiveness of the joint trajectories, optimizes parameters of the omnidirectional moving trolley and the three-dimensional linear inverted pendulum model, and finally realizes biped walking robot walking motion planning constrained by dynamics under a fast walking condition.