A medium and short distance, high speed and high precision pulse laser scanner which meets the first level of laser safety is designed for traffic data collection. To solve the problem of the laser scanner in rapid and high precision ranging, a digital full waveform pulse detecting method is proposed. The method judges the arriving time of the laser pulse by fitting the front edge of the laser pulse waveform. Taking the sampling clock of an Analog Digital Converter (ADC) as a counter, the delay of the laser echo signal is calculated. Then, according to the intensity of the laser echo signal, the ranging result is compensated. Thus, the Walk error is reduced greatly. The signal processing of the laser scanner is implemented on the basis of the high speed ADC and FPGA. The test results show that the laser scanner has its ranging frequency of 50000 points/s and its single point measuring precision is ±4 cm. It can meet the data collection requirements of automatic vehicle recognition, traffic flow investigation and passenger density detection.