The iterative algorithm is widely used in determining the parameters of photovoltaic models. In order to study the convergence speed of using the different iterative to solve the PV parameters, on the basis of brief introduction on the characteristics of NewtonRaphson and GaussSeidel iterative algorithms, combining with nonlinear transcendental equation for the output characteristics of photovoltaic models, the equations of the output parameters for the photovoltaic models are deduced in detail with NewtonRaphson and GaussSeidel iterative method. We use the equations to derive the PV parameters of three different photovoltaic modules and analyze and test these results. The results show that NewtonRaphson iterative method is insensitive to the selection of initial values and has faster convergence rate under the same precision. Such method is more suitable for the calculation of photovoltaic model parameters.