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The black soil region in Northeast China is rich in soil fertility, good in soil properties, and suitable for crop growth. However, the problem of soil erosion in sloping farmland seriously threatened the regional ecological environment and national food security. To discover the influences of the optimal amount and duration of biochar supply on water saving and yield increasing in slopping farmland of the region, the two years experiments were conducted based on runoff plot in 2015 and 2016. Five treatments were set according to different amounts of biochar, which were 0t/hm2(C0), 25t/hm2(C25), 50t/hm2(C50), 75t/hm2(C75) and 100t/hm2(C100), and the same amount of biochar for each treatment was supplied continuously in the next year. The results showed that biochar made the soil bulk density decreased, and the soil porosity and organic carbon density were increased sharply with the increase of biochar in two years. The field capacity was increased with the increase of biochar in 2015 while which was first increased and then decreased in 2016, and the best one was the treatment of C50. At the same time, the three-phase and generalized soil structure index (GSSI) were the most reasonable in C50 compared with others. The annual runoff in three degrees sloping farmland both were decreased in the two experiment years, and the annual runoff coefficient was decreased most, which was in the treatment of C75 (by 15.44%) in 2015 and C50 (by 17.27%) in 2016. The addition of biochar also could increase the soil water accumulation amount and decrease the rate and magnitude with time after rainfall. The highest yield of soybean was respectively C75 (27.16%) in 2015 and C50 (28.17%) in 2016. Compared the results in 2015 and 2016, the water use efficiency of soybean was increased by 27.67% with 50t/hm2 biochar supply for two years compared with the control treatment, and the effect of water saving and yield increasing of the treatment was the best one.