Abstract: Rapid urbanization has caused apparent change in surface energy balance due to large replacement of natural vegetation with artificial surfaces, which leads to the urban heat island (UHI) and deteriorates thermal comfort of urban residents. The outdoor thermal comfort assessment focuses on estimating people’s thermal sensation in outdoor environment by considering meteorological factors and individual activities. The results can be used to identify the high risk area suffering from thermal  stress in urban area and the valuable measures to mitigate harmful environment. In this paper, we systemically reviewed the development of thermal comfort theory and introduced indices used in thermal comfort analysis, the scientific basis of these indices and the existing problems. Then, how to improve thermal environment was analyzed from perspectives of street orientation, building layout and arrangement of vegetation and water bodies. Last, the limitations of  thermal comfort assessment were discussed, and the perspectives in thermal environmental study were given: (1) to improve the simulation accuracy of outdoor thermal environment evaluation model; (2) to develop uniform standards on field measurements and questionnaire surveys in thermal comfort researches in purpose of improving comparability of different studies; (3) to aware the disparities between thermal comfort levels and urban heat island intensities and take effective mitigation measures according to specific cases; (4) to consider thermal comfort by integrating temporal scale and spatial scale, and propose overall and feasible strategies to improve urban thermal environment.

Key words: cut chrysanthemum, continuous cropping obstacle, bio-organic fertilizer, fungicide, cut chrysanthemum quality, soil enzymatic activities.