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The small hillside crawler tractors (abbreviated as SHCT) often encounter obstacles such as steps, masonry, and ridges when driving in the field, which seriously affects the passability and driving stability, and may even cause safety problems such as side slip and overturn. In order to solve this problem, the movement process of the SHCT climbing over the step was analyzed, and the mathematical model of the maximum obstacle clearance height was established. Its value was used as the evaluation index of the obstacle negotiation performance of the SHCT. Then, orthogonal and single variable simulation tests were carried out by using RecurDyn. The results indicated that the slope angle, the tractor speed and the centroid position significantly affected the maximum obstacle clearance height;and increasing the tractor speed and decreasing both the slope angle and the center height can improve the obstacle negotiation performance. Finally, a test using a self-developed 18HP SHCT for the obstacle negotiation performance was conducted. The test results showed that when the speed was 1.6km/h and the slope angle was less than 15°, the test results were basically consistent with the theoretical calculation and the simulation results. The most relative errors of the theoretical calculation and simulation were 5.17% and 6.47%, respectively;while the slope angle was larger than 15°, the minimum relative errors were 13.25% and 19.21%, respectively. The results showed that the mathematical model and simulation model of the SHCT were both effective when the slope angle was small. It could provide a theoretical reference for the safety analysis for obstacle negotiation, structural improvements and farmland using of the SHCT on the slopes less than 15°.