To generate and control the FSK signal, a design method based on MCU is given. The hardware is simple and practical devices, such as W77E58 MCU, high precision DAC chip, MAX232 and the operational am? plifier. In order to ensure the more reliable work status, IMP813L chip is used to design the watchdog circuit. The software is composed of two parts: the communication programming of 3350 main board and the analog code pro? gramming of the signal generator. These softwares are supported by the hardware based on MCU, and the re? quired FSK signal can be outputted stably. According to the principle of this method, the chip can easily generate other analog signals. The good result in practical application can prove the rationality and the validity of this de?sign.