Abstract: Range accuracy is one of the most important parameters in a radar system. Research on the influence of range accuracy has an important value to improve the laser performance of radar. As a novel lidar system, linear gain modulation scannerless lidar acquires range information from image intensity by using the technique of range-intensity mapping. The relationship between range resolution and lidar system parameters was under investigated, taking different factors into consideration, including the modulation error of ICCD, the photonic noise at low echo intensity, the detector noise, and the gain saturation of micro channel plate. This paper presents that, within a certain region of echo signal power, range resolution can be improved by over twice that of outside the region, leading to great improvements of lidar system performance.