A special grassfeeding guide device for the disc lawn mower was designed for the coarse and difficulttocut weeds that are commonly grown in the orchard. Combined with CREO and ADAMS,the rigidflexible coupling model of grassfeeding guides and weeds was established,and the movement laws of weeds in the case of grassfeeding guide device with different angles and advance speeds were analyzed. According to the relationship between the displacement of the weed tip point in the X,Y and Z directions of the space coordinate system,three important indicators including the offset angle of the weed,the theoretical maximum cutting width of the mower and the cutting offset were calculated to characterize the working effect of the grassfeeding guide device. Using DesignExpert 10.0 software,a comprehensive test was designed,and the response surface effects of the three indicators were analyzed,and the experiments were verified and compared. The results showed that the optimal angle of the grassfeeding port was 80°,with the machine forward speed of 1 330 mm/s. At this time,the grassfeeding guide device worked well with flat cutting and the maximum offset of 27.02 mm.