Resolving power and signal to noise ratio are two key indicators of ICCD system. In order to analyze the influence of resolving power of ICCD, a high resolving power ICCD sample machine and a comparing ICCD sample machine were assembled. The resolving power and signal to noise ratio of two ICCD sample machines were measured in different illumination. The experimental result shows: when the illumination is above 1.84×10－3 lx, the resolving power of the ICCD system is under the influence of resolving power and signal to noise ratio of devices. The resolving power of high resolving power ICCD sample machine is higher than the comparing ICCD sample machine′s. When the illumination is below 1.84×10－3 lx, the resolving power of the ICCD system is under the influence of signal to noise ratio of devices. The resolving powers of two systems are equal.