Abstract: The study aims to relieve the forage shortage problem of livestock in winter and spring, effectively utilize the water, heat, light and land resources from August to October by multiple cropping forage fodder soybean, clarify the high-yield cultivation technique in autumn idle land and promote technology application of matching technology. Using orthogonal experiment method and PASW 18 statistics software, taking grass yield as the key measuring parameters, the authors compared the influencing factors of rowledge, density, nitrogen (N), phosphorus (P), potassium (K) and so on in autumn idle land. The results showed that density, rowledge and K had significant influence on the grass yield in autumn idle land. The optimum proposal of fodder soybean high-yield matching cultivation technique in autumn idle land was clarified as follows: leaving seedlings density was 750000 plants per hm2, and nitrogen (N) was 300 kg/hm2, phosphate (P2O5) was 112.5 kg/hm2, potash (K2O) was 375 kg/hm2 as basic fertilizer, 50 cm rowledge by sowing in line. In the proposal, fresh grass yield was 6661.67 kg/hm2, hay grass yield was 2723.64 kg/hm2, increase 24.17% and 27.63% than that of the second optimum proposal. The study could provide the theoretical basis and technical support for the production of fodder soybean in autumn idle land.