water temperature control system uses the Single Chip Microcomputer to carry on temperature real-time gathering and controling. DS18B20, digitized temperature sensor, provides the temperature signal by \"a main line\". In -10～+85℃ the scope, DS18B20’s inherent measuring accuracy is 0.5 ℃. The water temperature real-time control system uses the electricity nichrome wire carring on temperature increiseament and operates the electric fan to realize the temperature decrease control. The system has the higher measuring accuracy and the control precision, it also can complete the elevation of temperature and the temperature decrease control.