Abstract: In order to explore the short-term effects of different rates of rice husk biochar application on acid control and passivation of soil heavy metal cadmium activity in paddy fields, six application rates were set up in this experiment. The changes of soil pH, rice yield, soil available cadmium, cadmium content in stems and panicles of rice plants and soil fertility were analyzed and determined. The results showed that compared with CK, the application of biochar effectively increased soil pH by 0.15 - 1.04 units. When the application rate of biochar was 80 t·hm^–2, the effect of increasing soil pH was more significant. The application of biochar effectively improved the overall soil fertility. Soil total nitrogen, total phosphorus and total potassium increased significantly when biochar was applied more than 40 t·hm^–2, with an increase of 8.62% - 14.2%, 19.6% - 28.3% and 11.9% - 21.5%, respectively. Available phosphorus, available potassium and organic matter increased significantly when the application rate of biochar ≥20 t·hm^–2, with an increase of 34.6% - 115%, 70.9% - 394% and 29.3% - 118%, respectively. When the application rate of biochar exceeded 20 t·hm^–2, the content of hydrolyzable nitrogen decreased significantly by 11.4% - 22.1%. The biochar application effectively reduced the available cadmium in soil and the cadmium content in stems and panicles of rice plants when the application rate ≥20 t·hm^–2, with the reduction of 24.0% - 37.1%, 24.1% - 82.9% and 28.0% -78.3%, respectively. The cadmium content in rice leaves decreased significantly when biochar application rate exceeded 40 t·hm^–2, with a decrease of 22.1% - 35.7%. The biochar application increased the yield of rice. When the application rate was 20 - 40 t·hm^–2, the yield was significantly increased by 12.4% and 9.42%, respectively. In the short-term, rice husk biochar of 20 t·hm^–2 is with the potential to regulate soil acidity, passivate heavy metal cadmium activity and increase rice yield.