The invention discloses a somatosensory interaction method and a system thereof. Based on the somatosensory interaction system, the system comprises an external camera component and a mobile terminal.The external camera module comprises two cameras, a processor connected with the camera and a communication interface connected with the processor. The mobile terminal is connected with an external camera assembly through a communication interface. The optical axes of the two cameras are in the same horizontal plane. The method comprises the following steps of: acquiring human body images by twocameras; the processor calculating the depth information of each human body image point in the human body image, obtaining the depth map according to the depth information, and sending the depth map to the mobile terminal; the mobile terminal extracting the human body posture from the human body image according to the depth map and sending the extracted posture to the current somatosensory game application. The human body posture and the human body in the game are fused, and the fused picture is sent to the display screen of the somatosensory game. The user of the invention does not need the hand-held mobile terminal to carry out the action, and the convenience and the user experience of the somatosensory game based on the mobile terminal are improved.