Soil indoors model experiments were carried out to study effects of aluminum sulfate(Al_2(SO_4)_3) on improved effectiveness and forms of phosphorus.The results showed that different Al_2(SO_4)_3 amounts and the same amounts of phosphate fertilizer and nitrogen fertilizer could obviously promote emergence rate and growth of wheat.If amounts of Al_2(SO_4)_3 and nitrogen fertilizer were given,applying different amounts of phosphate fertilizer,emergence rate and growth of wheat didn't change significantly.Whether phosphate fertilizer application or not,curves of available phosphorus were all decreased with increment of Al_2(SO_4)_3.If amounts of Al_2(SO_4)_3 were given,available phosphorus contents were increased with increment of phosphate fertilizer.Fractions of inorganic phosphorus in original soil and improved soils were studied.The results showed that the sequences of components of inorganic phosphorus were followed O-P>Ca_(10)-P>Al-P>Fe-P>Ca_2-P>Ca_8-P.The application of phosphate fertilizer made the components of inorganic phosphorus changed greatly.The changeable sequences of inorganic phosphorus content of soils improved by different Al_2(SO_4)_3 amounts were followed Ca_2-P>Ca_8-P>Al-P>O-P>Fe-P>Ca_(10)-P.Under different Al_2(SO_4)_3 amounts condition,Ca_8-P and O-P were the valid complement of Ca_2-P;under different phosphate fertilizer amounts condition,Ca_8-P,Al-P and Fe-P became the valid complement of Ca_2-P.