In order to obtain continuous tunable high-frequency microwave signals, a high precision thermoelectric cooler (TEC) temperature control system is designed based on microcontroller. MSP430F149 is used as the control chip of the system. TMP112, a digital temperature sensor, is used to collect temperature information, and the temperature can be controlled by TEC chip driven by the pulse width modulation (PWM) signal from driven circuit. The steady error is about 0.06 °C. The optical fiber temperature is controlled by the temperature controller, and the high-frequency microwave signal from 10.872 GHz to 10.905 GHz is obtained by adjusting the temperature. The signal frequency shift magnitude slope is about 1.1 MHz/°C. A wider range of microwave signals can be obtained by increasing temperature tunig range of the control system.