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Aiming to explore the application effect and comprehensive effects of adding biochar for many years in the black soil region of Northeast China, find the best carbon application amount and application period, and provide scientific theoretical guidance for the efficient use of black soil resources and the sustainable development of water resources. In 2015, the research on the best application mode of biochar was carried out at Hongxing Farm in Bei`an City, Heilongjiang Province. Five treatments, including Y0 (0t/hm2), Y25 (25t/hm2), Y50 (50t/hm2), Y75 (75t/hm2) and Y100 (100t/hm2) were set according to the amount of biochar applied, and each treatment was repeated twice, and continuous application for four years (2015—2018), indicators of soil physical and chemical properties, soil and water conservation effects, and watersaving yield increase were observed. A projection model optimized by genetic algorithm was established to comprehensively evaluate the index. The results showed that with the increase of biochar application and application time, the soil bulk density showed a decreasing trend, soil pH and soil C/N showed an upward trend, and the larger the cumulative amount of biochar applied was, the more obvious the trend was. The field water holding capacity under the treatment of Y25 and Y50 showed an increasing trend with the increase of the application period. The Y75 treatment showed a trend of increasing first and then decreasing. The field water holding capacity under Y100 treatment showed a downward trend year by year, and the field water holding capacity under Y25 treatment in 2018 was 3733%, the runoff coefficient and soil erosion amount were both decreased first and then increased. The effect of 50t/hm2 biochar on reducing runoff and resisting erosion were the best. The yield of corn with 25t/hm2 biochar applied continuously for four years was the highest in all treatments, which was 10350kg/hm2. Through the comprehensive evaluation model, the best biochar application mode of 3263t/hm2 biochar applied to the northeast black soil area was obtained for three consecutive years. The results of this study can provide a theoretical basis for biochar to improve soil in black soil areas.