Abstract: The soil bulk density and moisture content are main factors influencing the draft resistance and power consumption of tractors.In order to study the quantitative relationship among them,three soil bulk density levels and three moisture content levels were determined within the limits of 1.1～1.7 g/cm^３ and 11 ％～19 ％ in the field respectively. The perpendicular tests of the resistance of shoe opener were designed. The tillage resistance and depth of shoe opener were measured by using the improved fifthwheel gauge and the DT 100f Datataker, and the soil bulk density and moisture content were measured by the bulk ring at the same time in the field. The test data were analysed through the Marquardt nonlinear curvefitting technique and a model representing the relationship among draft resistance, soil bulk density and moisture content was proposed. It has higher fitting precision and can be used to estimate the energy consumption and the draft efficiency under different soil conditions.