Abstract: Aiming at the low quality of rape straw laying, which could result in the uncontrollable afterripening and great lost of pick- up value, the 4SY- 2.2 rape windrower was designed to achieve dividing, cutting, conveying and laying operation. The authors analyzed the movement process of rape straw on and out of the cutting platform, and then determined the essential condition for smooth convey and cast of rape straw. The analysis of the movement curve of the dropping rape straw showed that the rape laying angel was related with its own biologic characteristics, windrower structural parameters and motion parameters. Field experiments showed that the laying of rape was orderly after windrower operation, the average value of laying angel was 48.4°, the average layer height was 511.6 mm and the width was 797.8 mm, the average height of the cutting stubble was 365.5 mm. It indicated that the laying quality could reach the requirement of after-ripening and pick-up operation.