A dynamic model of solar parabolic trough collectors has been developed and solved by explicit Euler's method to predigest partial differential equations to ordinary differentials in this paper. Different working conditions of the collector structure and thermal parameters have been considered in the model. The simulated results are validated using the selected real test data on typical summer and winter days, and the steam-generating process from unsaturated water to superheated steam has been studied in the startup simulation. The disturbance analysis validates the model's dynamic responses and confirms the relations between output steam characters and solar radiation, inlet water temperature, flow rate and collectors' area. The results indicate the possible demarcation point of superheated steam generating in different working conditions. Therefore, the model can be used to analyze the performance of the solar direct steam-generating system. Copyright (C) 2010 John Wiley & Sons, Ltd.