In order to keep the rotary tiller tilling stable with a depth consistency in field operation, a leveling mechanism is designed and test for 1 GDZ?150 crawler rotary tiller. The leveling mechanism is composed of a leverage mechanical part, a hydraulic system and an angle signal collecting device. When the rotary tiller is operating, the angle sensors detect the real-time angle and collect the data, which is filtered by using a combinational digital filtering algorithm. The synchronous hydraulic cylinder drives the lever mechanism to adjust the tiller’s angle and achieve leveling by a center fixed leveling method. The test results show that the leveling mechanism is working effectively and making the tiller cultivating on average deep of 11.34 cm with a variable coefficient of 3.7% for the tillage depth.