Aiming at the fact that the existing surface microtopography measuring device is difficult to achieve the accuracy and efficiency of surface measurement simultaneously after mechanical cultivation operations, a non-contact surface microtopography measuring device composed of LiDAR, linear guide, portable computer and bracket was developed. The stepping motor drive controller based on STM32 single-chip microcomputer was developed, and a complete acquisition system was built up combined with the upper computer software. The system can realize precise positioning of the LiDAR and quickly obtain the three-dimensional coordinates of the surface. The typical resolution of the device was 3.8~10mm in the LiDAR scanning direction, the vertical scanning direction can be arbitrarily set within the millimeter precision range, the ranging resolution was 1mm;the coverage area was 6.8m2 typically, when the vertical scanning direction resolution was 10mm, the single measurement time was less than 2.5min. By analyzing the source of measurement error, the system error compensation model was established. Under the condition of 15 mean filtering, the maximum absolute error of the device was 2.7mm and the maximum average absolute error was 0.9mm. The device was investigated on rapeseed surface area after direct seeding of the crop. Test results revealed that the surface three-dimensional model generated by Matlab can accurately reconstruct the original microtopography surface features, and the measurement results were consistent with the actual surface height fluctuation. The statistical analysis showed that for attaining stable results, the root mean square height and the correlation length in the fixed size area needed to be sampled 16 times and 64 times, respectively.