The soil incubation and pot experiments were carried out to study the effect of the five kinds of conditioners(lime,rape straw,organic fertilizer,potassiumsilicon fertilizer and soil conditioner,dosage for 1.8 g/kg)on acid soil(pH 3.9)acidity index and barley growth. The soil incubation experiment results showed that application of lime,organic fertilizer and potassiumsilicon fertilizer improved the soil pH obviously,while the content of exchangeable acidity,exchangeable H+ and exchangeable Al3+ were decreased significantly. The effect of lime was the largest,which increased pH by 0.66 unit,decreased the content of exchangeable Al3+ by 2.01 cmol/kg,respectively,compared with the control treatment; The effects of the organic fertilizer and potassiumsilicon fertilizer ranked only second to the lime,which increased pH by 0.14 and 0.15 unit,respectively,and decreased the content of exchangeable Al3+ by 0.23 cmol/kg and 0.19 cmol/kg,respectively,compared with the control treatment. From the point of acidity index,there were no significant differences compared with rape straw,soil conditioner and control. The results by the pot experiment on barely seeding showed that compared with the control,the shoot dry weight were increased respectively by 71.5%,24.1%,27.6%,28.2% and 24.7%,at those five conditioners,besides,the average height of barley,root length,root total surface area and root activity were significantly higher than those of the control,while,root mean diameter decreased,which is good for the absorption of nutrients and moisture. As a consequence,the effects of different types of conditioner on acid reduction were different,with lime working the best. The treatment of rape straw hadnt effectively reduced the acidity of soil,but obviously promoted the crop growth,which could be used as acidic soil improvement material. So in crop production,appropriate measures on application of various regulating substances should be adjusted to local conditions to promote crop growth.