The toxicity of aluminum (Al) in soils depends on its chemical forms. Tea (Camellia sinensis L.) is typical acidophilous and poly-Al plants. In order to understand the characters of Al in tea plantation soils, forms of active Al were studied based on the analysis of soil samples at different tea plantations in different years with sequential chemical extraction procedure, the transformation of Al forms and affecting factors for active Al in the plantation in the process of soil pH increased or decreased were discussed to understand the characteristics of Al. The results showed that digestion of active Al was enhanced during the soil acidification, the difference of Al contents in different forms were significant, decreased in the order of humic acid aluminum (Alh) > Al of hydrous oxide and hydroxide (Aloh) > exchangeable Al (Alex) > organic combined Al (Alo) > water soluble Al (Alw) > inorganic adsorption Al (Alino). Alh and Aloh constituted the dominant part of the total active Al, accounting for more than 80% of the total Al. Soil pH, organic matters and acid capacity were the important factors of Al forms. Aloh, Alino and Alw were translated into Alex during the process of soil acidification, but the situation was opposite with the increase of soil pH. Alo affected the transformation of other Al forms, the content of Alh decreased and was translated to Aloh with pH increased, on the contrary, the content of Alh increased with the process of soil acidification, meanwhile, it promoted the hydrolysis of Alino.