Abstract: Studied on the leaching phosphate rock by industrial-grade hydrochloric acid.A zero level orthogonal experiment had been designed by using three-factor second-order regression method.Consequently,a mathematical model was obtained.By this model,the effects of the concentration of hydrochloric acid,ratio of the practical dosage to the theoretical dosage of hydrochloric acid,and leaching time on the yield of P<SUB>2</SUB>O<SUB>5</SUB> can be estimated.And from this equation,the optimum reaction conditions were also obtained:the mass fraction of hydrochloric acid was 26%,ratio of the practical dosage to the theoretical dosage of hydrochloric acid was 105%,leaching time was 1.5 h,and the maximum yield of P<SUB>2</SUB>O<SUB>5</SUB> from phosphate rock could reach 98.45% under these conditions.