The invention relates to the technical field of pattern recognition and specifically to a human motion recognition feature expression method based on depth mapping. The human motion recognition feature expression method based on depth mapping is easy to implement, increases the accuracy of motion recognition, and comprises steps of: extracting, from a color image sequence of a motion-sensing video camera, a human motion space-time interest point p; computing a light stream feature and a gradient feature in the color image sequence by revolving around the human motion space-time interest point p; finding out, from a depth image sequence of the motion-sensing video camera, a corresponding human motion space-time interest point p' and acquiring the depth value of the p'; dividing the p into N layers according to the depth value of the p' and on the basis of a Gaussian mixture model, constructing multichannel expression based on depth mapping, clustering the space-time interest point of each layer by using a clustering algorithm and expressing the space-time interest point of each layer by using a bag-of-word model to obtain a histogram vector; and connecting the feature expression of each layer to form a feature S=(H1,..,Hi,..,Hn). The method is mainly used in the aspect of human motion recognition.