Abstract: A laserplane system has be developed for the auto levelling machine which is in great demand for high yields and increasing agricultural efficiency. First of all, the optical intensity and energy distribution of a semiconductor visible laser beam was studied. Then the difference of the sum light and the laser beam in scanning was investigated. Furthermore, the laser tansmitter, receiver and controller was designed based on the analysis. The test data indicates that the performance of the developed system is as good as that of the same kind of system produced abroad. The detection range is 200m, with a error of less than 1cm. This system can be used to level a plane, inclinedplane and dig ditch. It is suitable for irrigation,airport,railway,highway, and construction work sits.