Different climate assessment tools' features and application scope were analyzed to solve the problem of lack of climate assessment tools in the urban master planning scale. The WRF model's application method and validity was studied in urban heat island (UHI) evaluation. According to the demand of urban master planning scale, the method to generate WRF simulation boundary conditions with high resolution urban geographic and land cover data was established. The physics schemes for WRF high resolution simulation were also clarified. A typical summer hot weather day was taken as the research background in the coastal city of Dalian, the WRF model was used to simulate the UHI effect with the resolution of 300 meters. The results showed that WRF model could reproduce the intensity, temporal and spatial variation of UHI effect. The simulation results were compared with the data of weather station and the in situ observation, their change trend was found to be consistent and the deviation was within the acceptable range.