The Voigt profile function which is the convolution of the Doppler and Lorentzian function is investigated analytically and its maximum is obtained. The results indicate that the maximum of the Voigt profile function is smaller than maxima of Doppler and Lorentzian profile function, which is determined by the half-widths of Doppler and Lorentzian profile function. The Voigt profile function is a symmetric function about the central frequency. A new technique is presented, with which the Doppler and Lorentzian profile function can be obtained by using the maximum and half-width of the Voigt profile function, and the technique is verified by the Monte Carlo method.