The embodiment of the present disclosure discloses a method and apparatus for detecting frequency deviation of a clock. The method includes: counting the clock to be detected to acquire current counting information; filtering the current counting information to acquire filtered data; and acquiring the frequency deviation of the clock to be detected from the filtered data. According to the embodiments of the present disclosure, the detection accuracy of frequency deviation is improved by filtering the counting information acquired by counting the clock to be detected, and appropriately increasing an amount of information after the filtering, so as to perceive the occurrence of any abnormal dithering, and avoid neglecting of any abnormal condition in periodic or aperiodic queries.