The commercial pedestrian block, famous for its entertainment and commercial vitality, plays an important role in humans' daily life. The use of this space is determined by outdoor thermal comfort which can directly the commercial value of this region. So far, few studies have been conducted on outdoor thermal comfort in hot-summer and cold-winter area of southern China. The Dao He Old Block locates in Tai Thou city which belongs to hot-summer and cold-winter climate zone of southern China. In order to develop the local tourism, the local government has provided guidance for the appropriate directions and opportunities for future development of this region. This study investigates the thermal comfort conditions in microclimate of this block and put forward some suggestion for the tourists determine the best time to visit, also help managers choose their business hours. In this region, humans' thermal acceptability and the thermal comfort sensation votes are acsessed based on the Physiologically Equivalent Temperature (PET). About the future redesigning plan of this block is shown in three stages: increasing the building height; adding tree canyon coverage; changing paving material. Along with performing field measurement in this intended block, in addition, a three-dimensional microclimatic modelling tool ENVI-met 4.0 is used to evaluate the outdoor thermal comfort and validate the accuracy of the software through comparing the measured data with the simulated data. The existing scenario shows that almost the whole area is not comfortable for visiting from 8:00 am to 6:00 pm in extreme summer. After putting forward some suggestion for redesigning this area, the result shows that there is a strong improvement in broadening the cooling time, which means the more suitable time for visiting is given, the new result shows that early morning (8:00-11:00 am) and after 6:00 pm are the most comfortable time for visiting.