Abstract: In order to increase the consumption of renewable energy for electricity generation, using thermal power unit in peak shaving in power grid has become high frequency and normal. Frequent load fluctuation leads to higher energy consumption, lower control quality and serious equipment life loss. Therefore, it is urgently necessary to carry out an in-depth research on the transient characteristics of thermal power unit with variable load. In this paper, the models, simulation tools and related results in the research on transient characteristics of thermal power unit were sorted out. The existing problems, future research focuses and direction of the technology development and application were put forward. Currently, the researches rely heavily on simulation methods, and the transient models were lack of practical verification. There are only few researches that further propose control strategies based on transient characteristic evaluation. Thus, it is difficult to realize the conversion of achievements. In the future, the focus of the theoretical research is to promote the accuracy and rapidity of transient process evaluation for thermal power unit. The direction of the technology application and development is to organically integrate the research results of the models with intelligent power generation technology.