The phosphorus removal is a series complex biological and chemical reactions in actual wastewater treatment plant (WWTP). In order to analyze the effects of various factors on total phosphorus (TP) removal, response surface methodology (RSM) was used. The water quality parameters such as carbon/nitrogen ratio (C/N), carbon/phosphorus ratio (C/P), organic load ratio (F/M), and process parameters such as sludge discharge amount (m), agent dosage and external reflow ratio (R) were all investigated. Phosphorus balance model was also established according to the material conservation. The results showed the optimal ranges of C/N, C/P and F/M were 5.50~7.00, 50.00~70.00 and 0.06~0.08d^-1, respectively. From operation aspect, the optimal ranges of m, agent dosage and R were 14.3t/10⁴m³, 35~40mg/L and 65%~70%, respectively. Through analyzing phosphorus balance model, it was found influence degree on phosphorus removal was C/N, F/M, R, m, C/P and agent dosage from largest to smallest. When the main influence factors such as C/N and F/M were in optimal ranges, and WWTP was stable, the model could predict the effluent TP concentration precisely.