In order to understand the effects of long-term fertilization on the forms, distribution and availability of phosphorus (P) in acid orchard soils, 87 soil samples were collected from pomelo orchards in Guanxi to investigate the effects of soil P accumulation on P forms and availability by using Chang and Jackson's inorganic phosphorus forms method. The results showed that soil P was abundant in intensive pomelo orchard, and soil available P increased significantly with tree age. In addition, there were significant differences in P forms among different depths. When soil total P was less than 0.5 g/kg, the main forms of P were organic-P and Fe-P, but with the increase of soil total P, Al-P ratio and content increased significantly. Multiple linear regression and stepwise regression analyses showed the significant correlation between Al-P and available P. In conclusion, orchard soil has formed a huge phosphorus pool with high availability, reducing P input properly can effectively reduce soil P content and economic cost, and improve ecological benefit.