Embodiments of the present disclosure disclose a clock frequency detection method and apparatus. The method includes: dividing a known internal clock frequency range of the system into n frequency intervals, where each frequency interval is corresponding to a frequency detection module, and n is an integer greater than or equal to 2; obtaining a current internal clock frequency of the system, and using the current internal clock frequency as a reference clock frequency; selecting a frequency detection module corresponding to a frequency interval according to the reference clock frequency; and detecting, by the selected frequency detection module, a to-be-detected clock according to a frequency offset range of the reference clock frequency. By using the present disclosure, a risk that an internal clock of the system is attacked may be reduced, and system security may be improved.