Response surface method was used in this study to analyze the competitive adsorption characteristics of phosphorus (P) and fluorine (F) in yellow soil of western Sichuan under different proportions of biochar, different initial pH, P and F concentrations in order to provide new ideas for soil F fixation and fertilization technology. The results showed that under competition, the effects of different treatment conditions were in the order of initial F concentration>pH>initial P concentration> biochar ratio on P adsorption capacity, and were in the order of initial F concentration>initial P concentration>pH>biochar ratio on F adsorption capacity. Considering the interaction between various factors, the optimal reaction conditions under the combined influences of pH, biochar ratio, initial P and F concentrations obtained by the response surface model were: pH 5.0, biochar ratio was 2.9%, initial P concentration was 144.0 mg/kg, and initial F concentration was 178.8 mg/kg. Under these conditions, the predicted P and F adsorption amounts were 949.6 mg/kg and 1 622.0 mg/kg, respectively.