Abstract: The rape windrower was a dynamic system that including many input and output variables. Windrow quality mathematical model was used to describe the correlation of windrowing and transporting. An analysis on the relationship of biological morphology, the maturity when rape windrowing, the structure parameters of transporting mechanism and windrowing mechanism were given. The effect degree of exhaust straw port on windrow quality during the winding was analyzed. The correlations of windrow quality with the velocity of machine moving, transportin device parameter and exhaust straw port parameters were made. The results of field test showed that rape in the height of 1.3-1.7 meters, and in the yellow ripe stage was much suitable for cutting. The ratio of reel pad peripheral speed and machine moving speed should be chosen in the range of 1.1-1.5. The ratio of conveyor belt speed and machine moving speed should be chosen in the range of 3.2-5.0. The working rhythm and speed of stalk on the conveyor belt controlled by the transverse stir device must be coordination with transporting speed of the conveyor belt. Under those conditions that mentioned above, the windrower could get the total loss of windrowing was less than 1%, the windrowing angle of rape stalk was less than 30°, the windrowing angle difference was less than 15°, and the windrowing quality could meet the requirements of the agronomy.