A 64-channel APD array LiDAR system based on the full-waveform sampling technology was constructed. The signal processing circuit is designed using discrete components, and the output signal of the circuit is sampled in full-waveform using a data acquisition card. The acquired waveform data is processed by a least-squares Gaussian decomposition method, and the distance and characteristics of the target are analyzed by optimizing the parametric calculations. A common optical path experimental platform was built to test the circuit output waveforms and range accuracy of all channels. The results show that the signal processing circuit meets the design requirements of low noise, wide bandwidth, and distortion-free amplification; the maximum RMSE of the system is 16.10 mm and the minimum is 8.47 mm. Finally, step imaging experiments were conducted to provide a reference for future development of larger APD arrays of non-scanning LiDAR.