The invention relates to a robot motion estimation method based on dense optical flow. The method comprises the steps of calibrating inner parameters and outer parameters of a camera, collecting image sequences and conducting distortion correction, solving the dense optical flow through the polynomial expansion method, purifying light flow, conducting coordinate transformation between image coordinates and robot coordinates, and estimating the motion speed of a robot. The robot motion estimation method based on the dense optical flow solves the problems that in the prior art, motion estimation precision is not high, robustness is poor on the conditions that illumination is uneven and motion is vague, and the function of the camera is restricted. According to the robot motion estimation method based on dense optical flow, the dense optical flow algorithm based on polynomial reduction is introduced, so that the precision of motion estimation is improved. The RANSAC algorithm is applied to the optical flow purification process, so that the robustness of the algorithm is improved. The monocular camera is used, and a lens is arranged downwards in an inclined mode, so that a robot is made to detect the condition ahead in real time, and convenience is brought to completion of tasks such as avoiding barriers and planning paths.