700 ℃ tangential firing boiler has serious flue gas temperature deviation problem. A 660 MW tangential firing boiler with 700 ℃ corners was numerically simulated by commercial Fluent software. Using the method of simulated orthogonal test,five factors,such as the anti-tangential angle of the over-fire air (factor A),the velocity offset of the over-fire air (factor B),the possible interaction between the anti-tangential angle of the over-fire air and the velocity offset of the over-fire air (factor A×B),the upward swing angle of the burner (factor C) and the deflection angle of the secondary air (factor D),were set at two levels for each factor,and the flue gas temperature deviation at furnace outlet was used as the test index for optimization. Three analytical methods,such as range,variance and weight matrix,were used to analyze the simulated data. The results show that the order of importance of each factor to the test index is:factor D > factor A > factor B > factor A×B> factor C,among which,the influence of factor D is very significant,that of factor A is significant,and that of the other three factors is not significant. The weight ratio of each factor is:factor A（0.184）,factor B（0.068）,factor A×B (0.033),factor C（0.024）and factor D（0.544）;the numerical simulation shows that the best combination of factors and levels is A2B2C2D1. Under this combination,the flue gas temperature deviation on the left and right sides of the outlet section of the boiler furnace is 6.6 K,and the flue gas temperature deviation on the left and right sides of the outlet section of the boiler furnace can be controlled.