The single electron transistor (SET) has become one of the most promising components in nanometer electronic functional devices because of its advantages of low power consumption, high speed and high integration. But due to the special features in structure, SET usually operates only in very low temperature, which prevents SET from being feasible devices. Therefore, it is very important to investigate SET which operates in room-temperature. In this paper, based on the analysis of working mechanism of SET, we calculate the conditions in which SET can operate in room-temperature, then prepare SET samples in laboratory. The measurement results show that the prepared SET can operate normally in room-temperature. The research findings will deliver a fine foundation for the practical application of SET.