The temperature distribution in heavy forgings during forging process plays an important role for insuring quality of heavy forgings . Because the temperature distribution in heavy forgings is affected by many factors, such as environmental temperature, holding manner and so on ,which is difficult to be predicted. Temperatures at different locations from center to surface of a forging during forging process were tested under the conditions of simulating the heating curve and different holding methods. Through analyzing test data, the temperature field in Mn18Cr18N retaining ring steel forging was established, and the curves of temperature difference varying with time and the temperature rate were obtained. The result shows the varying temperature field in Mn18Cr18N retaining ring steel forging , which has definite significance for forging the steel in practice.