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In order to find out the effects of applying biochar on soil structure, soil fertility and crop yield and its sustainability in the black soil region, the field runoff plot of 3° sloping farmland in the black soil region of Northeast China was taken as the research object, and a fouryear observation was carried out. 〖JP3〗In 2015, according to the amount of biochar applied, five treatments of C0 (0t/hm2), C25 (25t/hm2),〖JP〗 C50 (50t/hm2), C75 (75t/hm2), and C100 (100t/hm2) were set. The treatments were applied as the same amount of biochar in 2016, 2017 and 2018. The results showed that the soil bulk density was decreased gradually with the increase of biochar application and the porosity was increased gradually, and the longer the application period was, the more obvious the effect was. The generalized soil structure coefficient (GSSI) of the four consecutive years was increased first and then decreased with the increase of biochar loading, the soil threephase structure distance index (STPSD) was decreased first and then increased, and the maximum (minimum) value (98.31, 4.87) was obtained in the second year of C50 treatment. At the same time, the threephase ratio of soil was the closest to the ideal state. the contents of macroaggregates (R0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) for four consecutive years were increased first and then decreased with the increase of biochar loading. The decreasing trend was the maximum in the C50 treatment in the second year. The soil available potassium and organic matter were increased gradually with the increase of biochar application for four consecutive years, and the soil available nitrogen and available phosphorus were increased first and then decreased. The highest increase of soil available nitrogen and available phosphorus in each year were C50 (46.1%, 76.6%), C50 (46.4%, 85.4%), C25 (33%, 100.7%) and C25 (23.9%, 103.2%). The application of biochar for four consecutive years can increase the yield of soybean and its components. In the second year, the C50 treatment increased the maximum yield, the yield was increased by 33.3%, and the yield was the most sustainable. The sustainability yield index (SYI) was 0.871. The research results can provide theoretical support for actual production.