Crop straw non-burning and returning has become one of the most important moves for comprehensive realization of straw resource utilization. Aimed at problems of large quantity of straw stalks, difficult sowing of later crops, wrapped straw and high-power consumption by using traditional straw crushing-returning machine for rice and wheat rotation region in the middle and lower reaches of the Yangtze river, straw crushing and seed-belt classification machine under full straw mulching was developed in combination with the agronomic requirements of wheat seeding in rice-stubble field in Jiangsu Province. One trip to the field, it can complete the multiple operation processes of straw-stubble crushing, row-spacing stacking, seed-belt cleaning, and the follow-up seed bed treating, fertilizer sowing, soil covering and suppressing, etc. Key components such as straw pickup-chopping device, guide-adjusting device and transmission route system were designed and analyzed theoretically to determine the relevant structure and position parameters. Three-factor and three-level orthogonal performance test was carried out with setting rotation spindle speed n(A), guider radial distance τ(B) and machine ground speed v(C) as the influence factors, straw crushed rate ε1 and stubble cleaned rate ε2 as the evaluation indexes. It can be known from the orthogonal test that the importance order of the factors which affecting ε1 was A, C and B, and that affecting ε2 was B, C and A, the comprehensive choice optimum combination of working parameters was A2B2C2, that was n=2000r/min, τ=20mm,v=1.0m/s, and ε1=93.42%,ε2=92.71%, the machine reached the best working performance. Field validation tests under optimum parameter combination showed that the average ε1 and ε2 were 91.25% and 90.54%, respectively, which satisfied the technical standards and agronomy requirements. The research results can provide technical and equipment support for the realization of straw non-burning and fertilization utilization, which had considerable production and application prospects.