In order to realize the high-precision measurement of pulsed laser echo signal parameters, a weak laser signal detection system that can analyze the pulse width, real-time power and energy parameters of the signal is designed by using full waveform sampling technology. The system hardware platform uses a low-noise wide-dynamic range analog front-end for signal preprocessing. The system realizes data quantization and dynamic time-domain latch based on field programmable gate array, analog to digital converter and other modules. In order to reduce the cost of the hardware platform, a multi-frame accumulation algorithm based on nonuniform periodic trigger signal is proposed to reduce the distortion of waveform reconstruction caused by high discreteness of data on low sampling rate platform. By fitting and compensating the quantized data, the algorithm improves the calculation accuracy of the system laser signal parameters. The system detects the parameters of a pulsed laser with 3 ns pulse width and 9 μW peak power and compared with the high sampling rate platform. The results show that the calculation error of the proposed system for laser signal pulse width is about 0.041 ns, peak power calculation error is about 0.53 μW, energy integration error is about 4.52 fJ and uncertainty of repeated measurement with all parameters is less than 8%.