In this paper, we select K60 as the core of the system and OV7620 as the camera sensor, designing a real-time character detecting node for the intelligent control of air conditioning. Also, we use NRF24L01 as the radio frequency module, finally composing these nodes of the whole system by WSN(wireless sense network). Meanwhile, considering the storage and computing speed of embedded system, we apply OTSU dynamic binarization algorithm and SOBEL operators to make image processing of the acquired images by OV7620, and propose a human detecting algorithm based on frame difference method. The final experiment shows that the system can detect if someone comes or leaves in the detecting area with the range 2 meters, and sends the result to control center. Finally, we also show the experimental results of different detecting distance and make a short conclusion.