Laser radar development tends to focus on array imaging laser radars. Due to the restriction of array detectors and laser power, it is hard to realize imaging with high resolution in distant range. Risley prism scanning imaging laser radars based on small scale array, possessing both the advantages of high resolution in array imaging laser radar and imaging in distance in scanning laser radar, have drawn much attention in laser radar researches. A small scale array Risley prism scanning imaging laser radar system is constructed with a high frequency solid laser transmitter and a double optical prism scanner for theoretical experiments. The system adopts a 5×5 array detector as the sensitive unit and designs a 25-channel parallel amplifier. The bandwidth of 200 MHz and 40 dB gain are achieved with the plastic circuit output signal jitter being less than 2 ns. The frequency of the 25-channel array timer achieves 200 MHz. These realize the small plane array block scanning laser radar principle experiment system. With the system, an indoor imaging experiment is presented. The results show that the ranging accuracy of the system reaches 0.8 m with a 3°×3° viewing angle and a 128 pixel×128 pixel image resolution. It analyzes the factors to influence the accuracy of block scanning imaging laser radar system according to the experimental results. The results show that the beams pointing accuracy, the bandwidth and timing accuracy of the scanner probes and processing circuit have the primary impacts on restriction of distant imaging quality.