Some field testing data of important operation points are provided by manufacturers of photovoltaic panels， but it is not enough for the simulation study of photovoltaic power generation system because detailed and accurate parameters of photovoltaic panel model are required. To calculate the parameters of photovoltaic panel model， a Newton-Raphson method is presented in this paper. All the information needed by the method are the data sheet values usually supplied by manufacturers of photovoltaic panels， in which the data of three special operation points of the panel such as the open-circuit point， the short-circuit point and the maximum-power point， can be found easily. Based on these data， the parameters can be worked out in a few steps of iteration. In order to solve the singularity problem appearing in the inverse matrix of the Jacobian matrix， a technique to modify the algorithm is proposed. Simulation study on a practical photovoltaic panel demonstrates the validity and simplicity of the method proposed.