Abstract: For tackling the problem of soil acidification in tea garden, different formulations of conditioners were used for soil improvement. The field experiment was carried out with tea variety Yinghong No. 9 planting 2 years (young tea garden) and 8 years (mature tea garden). Four different treatments were set up: no application of conditioner (CK), conditioner I (biochar, T1), conditioner II (biochar + lime, T2) and conditioner III (biochar + alkali residue calcium magnesium fertilizer, T3), with the application rate of 20 t·hm⁻². Soil analysis showed that, compared with the control group, the soil pH of the two tea plantations increased first and then decreased. Four months after treatment, the soil pH of the young tea plantations with conditioner I, II and III increased by 0.11, 0.20 and 0.22 units, and that of the mature tea plantations increased by 0.15, 0.16 and 0.38 units. However, 16 months after the treatments, the pH value decreased gradually. The content of soil available P and K in young tea garden increased significantly, but only available K in mature tea garden increased significantly. The results of tea quality analysis showed that compared with the CK, the water extract content of young tea garden treated with carbon-based conditioner increased significantly by 6.66%, 6.30% and 6.80%, respectively. In conclusion, the application of carbon-based conditioners would improve the acid soil, increase soil fertility and the internal substance content of tea.