Abstract: Abstract: One kind of agricultural machine was researched to harvest corn stubble. This machine consists of three subsystems: the excavating subsystem consists of a stubble spade and stubble push device; the stubble soil separation subsystem consists of a fist level screening conveyor chain, fixed roll, and second level screening conveyor chain; and the stubble collect and dump subsystem consists of a stubble collector container and dumping device. The screening conveyor chain is very important to the machine, as in the course of conveying corn stubble, the appearance of slipping off, piling up and clogging affected the harvest performance. In order to improve the dither mechanism performance of conveying corn stubble, the method of Combing theory analysis and experiment research was used to optimize the mechanism. Firstly, the dynamic model of corn stubble which is on the jitter chain was established, then the moving up and jumping critical condition of corn stubble were determined; Secondly, according to theoretical model and structural parameters of the whole system, the theoretical optimum parameters were obtained. The tilt angle of the mechanism is 23°, the rotational speed of driving wheel is 120 r/min, and the height of the chain is 34 mm. At last, by means of a test stand of dither mechanism and high-speed photography system, the moving up and jumping course of corn stubble were recorded and analyzed, The test results show that corn stubble can move up with jitter chain collectively, and corn stubble also can jump steadily.