Forming grinding process is a crucial method for grinding the helical flute of end mills, and the calculation of the grinding wheel profile is the key to ensure the precision of the helical flute, which is constrained by grinding wheel posture and helical flute profile. However, the current calculation method has not done enough research on the estimation of the feasibility and validity of the grinding wheel profile, which could lead to contradiction between theoretical calculations and practical application. In this paper, an optimized calculation method of the grinding wheel profile for the helical flute forming grinding is proposed, which includes the calculation, analysis and optimization process. Firstly, the parameters of the helical cutting edge and the flute surface are defined, and accurate geometrical models are established. Secondly, the contact condition between the grinding wheel and the flute surface is deduced to calculate the grinding wheel profile by the envelop theory. Thirdly, an optimization method, including profile optimization and grinding wheel wear optimization, is proposed for the calculation of the grinding wheel profile. Finally, the method is verified by simulation machining and the results show that the method can improve the grinding precision and expand the application range of forming grinding technology in helical flute grinding.