Abstract: Abstract: Under the environment of protection ploughing, this research designed a kind of test bench on which the sweep and tilt angles of disc coulter can be adjusted precisely in order to study the working performance of different kinds of passive disc coulter: general disc coulter, big ripple disc coulter, notched disc coulter, etc. Simultaneously, this research did four factors and three levels of orthogonal tests by using the factors of the type, velocity, sweep angle, and tilt angle of disc coulter and the evaluation indices of cutting rate and traction resistance. The optimal combination of parameters was achieved through orthogonal tests. Besides, the optimal combination of parameters was repeated verification tests. Fewer factors and levels were studied in this test. And it would take a longer time to do the test if we did a comprehensive test. Therefore, it was a reasonable choice of the orthogonal test. The principle of orthogonal tests was the use of scientific methods to select some representative points so that the points were distributed evenly within the test range. The test could reflect the full test case. Its advantage is to ensure the expected results of the test under the premise of reducing the number of tests and shortening the test cycle. Four factors of this test study were identified through theoretical analysis and access to a large number of relevant literature. Three levels were determined based on relevant literatures and pre-tests. There was no interaction between the factors of this test. So the L9(34) orthogonal table was selected. The results showed that the test bench can adjust the sweep and tilt angles of disc coulter precisely. The adjustment accuracy of sweep angle is 2.5° and the adjustment accuracy of tilt angle is 1°. In the three types of disc coulter, the big ripple disc coulter has the best cutting effect and the notched disc coulter consumes the greatest traction resistance. The primary and secondary order of the effects of every factor on cutting rate and traction resistance is the type, tilt angle, velocity, and sweep angle. The disc coulter type has a very significant effect on the cutting rate and traction resistance. Sweep angle has a minimal impact on the cutting rate and traction resistance. So in terms of cutting rate and traction resistance, it is essential to select the disc coulter type. For the passive disc coulter, the effect of forward speed on cutting rate is not as high as possible in the low speed range. Excessive speed can cause disc coulter slip rates to increase. As a result, the cutting rate will decline. At a given level, the optimal combination of the passive disc coulter is using big ripple disc coulter with the velocity of 5 km/h, sweep angle of 5°, and tilt angle of 2°.. The cutting rate is 86.17% and the traction resistance is 3 296.53 N. There are slashing cutting actions and sliding cutting actions of the three types of disc coulter. In the low speed, the cutting rate effect of sliding cutting action is better than slashing cutting action; the working performance of different types of passive disc coulter under different working conditions is different. This study may provide the basis for the relevant product design.