Basic Oxygen Furnace (BOF) steelmaking is the main method for steelmaking production, mixing efficiency of BOF vessel would greatly affect the uniformity of chemical composition and temperature in molten steel. Therefore, this paper conducted the effect of blowing parameters on bath mixing efficiency during BOF steelmaking process. Through measuring the mixing time of steel bath in BOF vessel, the effect of different blowing parameters was studied. Based on analysis of variance for the experimental results, the influence degree on mixing efficiency by different blowing parameters was acquired, and the optimized combination of blowing parameters was obtained. Moreover, the mixing index which indicated the mixing degree of steel bath in BOF vessel was proposed in this study, and an apparent nonlinear relation was acquired after determining relationship between the mixing index and blowing parameters. The optimal blowing parameters were applied to an 80 t industrial BOF vessel in a special steel plant, the end point carbon and oxygen equilibrium was decreased from 0.0032 to 0.0026, end point phosphorus and total Fe content in slag were reduced by 0.0012% and 2.21%, respectively. The mixing index and results presented in this work could be helpful to improve mixing efficiency in commercial BOF vessels.