The present invention provides a Voigt line shape fitting method, including step 1: Calculate a Gauss line shape function and a Lorentz line shape function, and calculate a Voigt line shape function. Step 2: For determined line shape parameters to be fitted, calculate partial derivatives of the Voigt line shape function with respect to the parameters, convert a partial derivative of the Voigt line shape function with respect to a parameter into a partial derivative of the Gauss line shape function or the Lorentz line shape function with respect to the parameter. Step 3: Substitute the Voigt line shape function and the partial derivative of the Voigt line shape function with respect to the parameter to be fitted, into a least squares algorithm step, perform least squares fitting calculation, and determine whether to terminate the least squares fitting calculation or return to step 1 to perform next iterative calculation.