As conventional imaging systems suffer from the excessive noise from Analog-digital Converters(ADCs) at low signal levels,this paper proposed an imaging method based on Geiger-mode single photon counting Avalanchen photodiode(GM-APDs) to realize all-digital detection of weak optical signals. The photon response model for the GM-APDs was established,and the performance of GM-APDs with dead-time effects was analyzed by using Markov renewal process. Then,the relationship between the digitlal pulse frequency measured by GM-APD and the input photon rate was deduced.Furthermore, a 2D scan imaging system was also built to verify this method. In the experiment, the photon counting images with different input photon rates were obtained. By using standard mutual information to assess image quality, it is demonstrated that the experimental system can achieve visual imaging with an input photon rate of 3.0×104 count/s, and the value of standard mutual information is over 0.5 with 2.7×105 count/s. It concludes that this system can realize photon counting imaging at low signal levels efficiently.