In order to develop environmental-friendly amendment, a phosphorus(P) modified-biochar composite (ROP) was prepared from rice husk and oyster shell powder, and a pot experiment was conducted to investigate the effects of ROP addition on the properties of acidified soil and the growth of Chinese cabbage. Results indicated that the addition of ROP could mitigate soil acidity. In soils adding 50 g/kg ROP and two different doses of fertilizers, soil pH was increased from 4.20 and 4.39 to 6.48 and 6.00, respectively. Meanwhile, the concentrations of organic matter, nutrients like P, and the activities of phosphatase and urease were increased in ROP amended soils, while the concentrations of available heavy metals were decreased. For Chinese cabbage, the dry weight of aboveground parts of plants under ROP treatment was 4.5 times higher than the control, and the concentrations of N, P and K were increased by 13.4%-31.6%, 119%-141% and 28.5%-81.1%, respectively. In conclusion, the application of ROP can improve soil quality, and alleviate the threat of soil acidification to plant growth.