Aiming at the problems of high requirements in supporting machine and poor adaptabilityto field condition and characteristics of rape for windrower , the 4SY–2.0 self-propelled rape windrower was been module designed based on the analysis of the conditions under that the rape been cut smoothly, transported continuously and laying orderly. The windrower mainly composed of power unit, walking device, working device and controlling unit. A small caterpillar undercarriage was used as power device to achieve good performance of passing and operating. A vertical header was adopt to adjust the cutting height according to different terrains and rapes’ conditions. After being cut, the rapes are transferred erectly then placed and spread to the sides of the cutting platform by the carrier chains . Field experiment has been done, and the result showed that the windrower could complete the work of cutting, conveying and laying. Rapes could be conveyed smoothly and windrowed orderly with uniform spreading in width and thickness. The average value of laying angle was tested to be 98.2° with the average laying angle difference of 10.5°, the average layer height of 416.6 mm, and the average laying width of 1 207.6 mm. It is shown that all working quality index reached the windrower standards.