The present invention provides an EMI automatic adjustment device and an EMI automatic adjustment method. The EMI automatic adjustment device comprises a crystal oscillator, a jitter clock generation unit, a PLL circuit, a spectrum spreading direction and scope configuration unit, a clock random number generation unit, a configuration random number generation unit, a configuration information control unit, a random seed generation unit, a high precision temperature ADC sensor, a change cycle configuration storage unit, a random number switch unit, a configuration information storage unit, and an EMI monitoring unit. EMI is automatically checked, or the spectrum spreading processing of PLL is carried out according to a configured EMI frequency point, the spectrum spreading operation of a clock is carried out through a configurable frequency spreading direction, thus original spectral energy spike is flattened, and an EMI problem is solved.