The invention provides a parabolic trough type condenser modeling method based on Monte Carlo and coordinate transformation combination. The method comprises the following steps: establishing a model framework of a parabolic trough type condenser model; establishing a parabolic trough type condenser energy flux density modeling flow; initializing the distribution condition of an incident light cone on the parabolic trough type condenser and the distribution condition in a sunlight cone by using the Monte Carlo method; establishing a direction and position model of incident light by using a coordinate transformation method; establishing a direction and position model of reflected light by using the coordinate transformation method; and establishing a model of tracking error of the condenser and a mounting error of a high-temperature vacuum heat adsorption tube. By adoption of the parabolic trough type condenser modeling method provided by the invention, the optical properties of the parabolic trough type condenser can be accurately simulated, the influence of tracking and mounting errors of a concentrating heat collection system to the energy flux density distribution is simulated, the parabolic trough type condenser modeling method can be applied to the concentrating heat collection systems in tower type, disk type and linear Fresnel solar thermal power generation systems, and provide theoretical calculation reference for converting optical energy into thermal energy in the concentrating heat collection system.