Acidic soil was used to study the effects of potassium silicate-modified biochar on the speciation of aluminum（Al） in soil and the growth of crops.7 treatments including CK （no biochar），0.5% raw biochar （0.5% unmodified biochar，0.5% CBC），1% raw biochar （1% CBC），2% raw biochar （2% CBC），0.5% potassium silicate-modified biochar （0.5% S-CBC），1% potassium silicate modified biochar （1% S-CBC），and 2% potassium silicate modified biochar （2% S-CBC） were set up for pot experiments to plant wheat and measure soil properties，with 4 replicates per treatment.The results showed that the effect of S-CBC on promoting the growth of wheat was higher than that of raw biochar.The root vitality of wheat seedlings treated with 0.5% S-CBC significantly increased by 103.0%.The single-spike weight of wheat treated with 0.5% S-CBC significantly increased by 8.61% compared to that with 2% CBC.S-CBC treatment significantly reduced the content of aluminum in wheat plants and increased the absorption of silicon by roots of wheat.The addition of biochar significantly decreased the content of exchangeable acids in soil.0.5% S-CBC treatment decreased the content of exchangeable acid by 29.17% and promoted the conversion of active aluminum to inactive state compared to 2% CBC treatment，indicating that the effect of S-CBC is significantly stronger than that of CBC.Biochar increased exchangeable base cations in soil，and 0.5% S-CBC treatment increased exchangeable K⁺ by 87.96% compared to 2% CBC treatment.Biochar increased microbial activity in soil and changed the composition of bacterial community，with soil pH and exchangeable Al3? （Ex-Al3?） identified as key factors affecting the richness of microbial community.Overall，the addition of S-CBC improved soil fertility，alleviated soil acidity，increased microbial activity in soil，and thus promoted the growth of wheat.The best effect was achieved with the addition of 0.5% S-CBC to the soil tested.