Peanut seedlings has many advantages as husbandry forage, such as rich nutrition, soft texture and low price. However, residual film on the harvested peanut seedlings that mulching cultivated would seriously affect the digestive system functions of livestock and reduce the feed utilization value of peanut seedlings. Therefore, it’s an urgent issue to carry out the research on removing the residual film from peanut seedlings. There are significantly differences on the components and suspension velocities of mixture materials that shredded by peanut seedlings shredding and residual film sucking machine, which make it difficult to separate residual film out from peanut seedlings. The suspension velocities of shredded materials are the basic characteristics during the research of improved design and parameters optimization for the device of separate residual film out from peanut seedlings. In view of the outstanding problems at present, for example, it’s hard to separate residual film form peanut seedlings and the materials loss rate is higher than that was expected. The suspension velocity measurement experiment was designed and conducted by using DFPF-25 type suspension velocity testing equipment, the physical characteristics and suspension velocities of materials that shredded by peanut seedlings shredding and residual film sucking machine were studied, and a kind of residual filmseedlings separating device of which combined centrifugal fans and vibrating sieve was designed, with the functions of grading, dust cleaning, material conveying and residual film sucking. The rotational speed of upper fans were designed to be 700~900r/min adjustable, that of lower fans were 500~700r/min adjustable, and the frequency of vibrating sieve was 3~4Hz adjustable. By using the peanut seedlings shredding and residual film sucking machine as the experimental platform, the performance test and parameters optimization of the residual filmseedlings separating device were carried out. The quadratic regression orthogonal test of threefactor and threelevel was designed by taking the rotational speed of upper fans, lower fans and the frequency of vibrating sieve as experimental factors, and residual film removal rate and materials loss rate as response values. The quadratic polynomial response surface regression models were established and optimized via the optimization modules of DesignExpert 8.0.6. The results showed that the significance order of the influence of test factors on residual film removal rate was as follows: the rotational speed of lower fans, the rotational speed of upper fans, and the frequency of vibrating sieve; the order of the influence on materials loss rate was as follows: the rotational speed of lower fans, the frequency of vibrating sieve, and the rotational speed of upper fans. The validation test results presented that the residual film removal rate was 91.24% and the materials loss rate was 8.51% when the rotational speed of upper fans was 760r/min, the rotational speed of lower fans was 670r/min, and the frequency of vibrating sieve was 4Hz. The relative error between the validation test results and the predicted values of the models was less than 5%, which proved that the models were reliable. The research result can provide reference for design and optimization of the residual film-seedling separating device of peanut seedlings shredding and residual film sucking machine. 