The invention discloses a determination method of a total heat transfer coefficient of a condenser of a thermal generator set. The method is as follows: generator set load, circulating water flow, circulating water inlet temperature, the practical total heat transfer coefficient of the condenser, the total theoretical heat transfer coefficient of the condenser are input into a preset multiple regression equation under multiple test working conditions; and the coefficient of the equation is determined and the condenser heat transfer integrated revision factor of the condenser is obtained, so that the deviation influences among the structural characteristics, the operating condition and the theoretical value of the condenser are revised. In the determination method provided by the invention, the modifying factor is used so as to modify the total theoretical heat transfer coefficient which is calculated by a traditional empirical equation, of the condenser, and the total heat transfer coefficient with small error, of the condenser can be obtained, thereby improving the accuracy of energy-saving diagnosis and optimization management of the cold end system of the generator set.