Abstarct: The increase in population and the expansion of urbanization, the reduction of green spaces, the high consumption of fossil fuels, the emission of greenhouse gases and the use of inappropriate materials have created the microclimate of the heat island over the cities; which made the air of the city several degrees Celsius warmer than its surroundings (villages). Outdoor thermal comfort is the key to creating vibrant outdoor urban spaces. The quality of thermal comfort of outdoor space depends on various factors, the sum of these factors together can be effective in improving the thermal comfort of outdoor space. In this research, in order to investigate the thermal comfort of outdoor space and the factors affecting it, Envi-met software has been used. Also, Valiasr residential complex of Mashhad was selected as a case study and the evaluation of thermal comfort conditions in the hot season of the year has been done. For this purpose, with the aim of validating the results, the field collection of environmental information, which includes the measurement of the main climatic parameters, has been carried out in two points of the complex environment (shade of trees and sunlight). In the continuation of the simulation process, the Physiological Equivalent Temperature Index (PET) has been used as the main index of thermal comfort. Also, in order to simulate the environment to obtain detailed information baxsed on real conditions, 5 blocks of the residential complex have been selected to control the data and ensure the accuracy of the simulation results. Field studies show that the temperature difference of the existing situation compared to the simulation model is maximum 2 °C, which indicates the accuracy of the recorded data and the simulated model. The results of the research in 6 scenarios which include facade materials, flooring materials, green wall, green roof, pergola and tree respectively show facade materials 0.7 °C, green roof 1 °C, green wall 1.5 °C, flooring materials 1.9 °C, pergola 8 °C and tree up to 10.5 °C compared to the current situation, the physiological equivalent temperature (PET) has decreased. Therefore, it can be concluded that creating shade by pergola and trees reduces the amount of PET as well as thermal stress in the hot season and increases the level and hours of thermal comfort during the day.