Abstract: Abstract: In order to study the tractive performance of lightweight vehicle on soft ground, this research aim at establishing tractive trafficability predicted model through soil bin tests under light load. This paper adopt the condition of light load with wheel load ranging from 30 to 90 N, the wheel sinkage, drawbar pull and tractive efficiency were taken as experimental indices, the wheel diameter, load and slip ratio were as experimental factors, and the regression orthogonal experiment scheme was designed. The effects of experimental factors on wheel tractive trafficability were also analyzed. Results showed that the wheel sinkage increased with the decrease of the wheel diameter or the increase of the wheel slip ratio and load, and the average relative increase rates were 14.3%, 36.9% and 77.4%, respectively. Results also indicated the wheel load had the most significant influence on the experimental indices, and the confidence coefficient value was up to 90%. Through the mentioned analysis above, a linear regression equation of wheel sinkage between wheel diameter, load was obtained. Compared with the measured and predicted values of wheel sinkage, both the residual error and the relative error of the two increased with the increase of the wheel load or the decrease of the slip ratio. The maximum residual error was less than 6.5 mm, and the range of the relative error was 1.4%-17.9%. Therefore, the linear regression equation could be used for the wheel sinkage prediction. In order to study the effects of wheel load and diameter on its tractive trafficability, experiments were also carried out when wheel load was 60 N and wheel diameter was 250 mm, separately, while the slip ratio range was 5%-60%. Results showed that the average increase ratio of the wheel drawbar pull was up to 29.71% with the increase of the wheel diameter, and it increased by 2.63 and 2.95 times with the increase of the wheel load and slip ratio, respectively. The wheel load had the most effect on the traction efficiency, the slip ratio secondary, and then the wheel diameter. When the wheel load was 60 N, the average value of maximum traction efficiency was about 0.23, and the corresponding slip ratio was 26.86%. From the results and analysis above, this paper suggests that the wheel load should be greater than 60 N to ensure the wheel traction efficiency is above 0.2, and the slip ratio between 10% and 40% is reasonable for a preferable tractive trafficability. Based on the traditional sinkage model and the linearization formula of wheel-soil contact stress distribution, and combined with testing results, a new sinkage model was established, which was suitable for the wheel slip conditions. The improved model has comprehensively considered the effects of the factors on the wheel sinkage, including wheel diameter, load, drive torque, drawbar pull and slip ratio. The range of the relative error between the model calculation values and experimental values was 0.8%-11.7%, the mean values of the relative error and the maximum residual error were less than 7.2% and 4.5 mm, respectively. Therefore, the improved model can be more accurate in the prediction of wheel sinkage, compared with the linear regression equation aforementioned. It is also appropriate for the predicting of wheel tractive trafficability. The research results of this paper provide technical methods and basic data for the development of light-weight vehicles and wheel tractive trafficability assessment under the condition of light load.