A temperaturecompensated crystal oscillator system based on MCU is designed in this paper. It has the features of visualization, high accuracy and temperaturecompensated mode adjustable. The MCU reads the realtime temperature and frequency data through temperature measurement circuit and frequency meter respectively at the wide temperature range of -6.9 ℃ and +72 ℃, and compares with the stored voltagetemperature curve, then generates control signal to compensate frequency shift of the oscillator. While the temperature is outside this range, the keyboard inputs refrigerating/heating signal according to the semiconductor refrigerating and heating circuit and adjusts the internal temperature to the proper range. The test result shows that the frequencytemperature stability is increased to ±1.875×10-6 from ±6.25×10-6 before compensating a the temperature range of -6.9~+72 ℃, which is promoted by 70%.