Abstract: Laser leveling technology offers many benefits in terms of increasing water utilization efficiency and crop yields. A laser leveler was developed for paddy field using a specially designed harrow connected to a tractor by means of a hydraulically driven 3-point linkage mechanism and a leveling control system where a tilt sensor was installed in addition to an ordinary laser system. The movement of one of the two cylinders of the linkage mechanism was controlled by the laser system, and the other cylinder was governed by a control circuit according to the signal from the tilt sensor fitted onto the harrow to indicate the degree to which the whole harrow was out of balance horizontally. The latter cylinder controlled the corresponding end of the harrow to track the other laser controlled end and keep horizontal balance of the harrow. The structural design and operation principles both mechanically and electronically were introduced in the paper, and the test results were also included. Field tests showed that the independent control of the two cylinders was necessary and it was more economical and more convenient in paddy field.