A safety monitoring system for human-machine symbiosis is provided, including a spatial image capturing unit, an image recognition unit, a human-robot-interaction safety monitoring unit, and a process monitoring unit. The spatial image capturing unit, disposed in a working area, acquires at least two skeleton images. The image recognition unit generates at least two spatial gesture images corresponding to the at least two skeleton images, based on information of changes in position of the at least two skeleton images with respect to time. The human-robot-interaction safety monitoring unit generates a gesture distribution based on the at least two spatial gesture images and a safety distance. The process monitoring unit determines whether the gesture distribution meets a safety criterion.