A frequency offset detection method, comprising: calibrating a frequency offset of a clock signal output by a local crystal oscillator of a network element device; and performing frequency offset detection on a tracked reference clock signal by using the calibrated clock signal output by the local crystal oscillator, wherein the calibrating a frequency offset of a clock signal output by a local crystal oscillator of a network element device comprises: calculating an external calibration value EXT_CAL according to a first count value X on a first counter and a first reference value X 0, wherein X denotes a count value obtained, when a reference clock signal input to the local crystal oscillator through an external clock interface has no frequency offset, by the first counter by counting rising edges of the clock signal output by the local crystal oscillator, X 0 denotes a count value obtained, when the clock signal output by the local crystal oscillator has no frequency offset and the reference clock signal input to the local crystal oscillator through the external clock interface has no frequency offset, by the first counter by counting the rising edges of the clock signal output by the local crystal oscillator, and X 0 = A × f 0 f, wherein A is a first preset count value, A is determined according to required precision of calibration performed on the frequency offset of the clock signal output by the local crystal oscillator, f 0 denotes a frequency existing when the clock signal output by the local crystal oscillator has no frequency offset, and f denotes a frequency existing when the reference clock signal input to the local crystal oscillator through the external clock interface has no frequency offset; and performing, according to EXT_CAL, external calibration on the frequency offset of the clock signal output by the local crystal oscillator. calibrating a frequency offset of a clock signal output by a local crystal oscillator of a network element device; and performing frequency offset detection on a tracked reference clock signal by using the calibrated clock signal output by the local crystal oscillator, wherein the calibrating a frequency offset of a clock signal output by a local crystal oscillator of a network element device comprises: calculating an external calibration value EXT_CAL according to a first count value X on a first counter and a first reference value X 0, wherein X denotes a count value obtained, when a reference clock signal input to the local crystal oscillator through an external clock interface has no frequency offset, by the first counter by counting rising edges of the clock signal output by the local crystal oscillator, X 0 denotes a count value obtained, when the clock signal output by the local crystal oscillator has no frequency offset and the reference clock signal input to the local crystal oscillator through the external clock interface has no frequency offset, by the first counter by counting the rising edges of the clock signal output by the local crystal oscillator, and X 0 = A × f 0 f, wherein A is a first preset count value, A is determined according to required precision of calibration performed on the frequency offset of the clock signal output by the local crystal oscillator, f 0 denotes a frequency existing when the clock signal output by the local crystal oscillator has no frequency offset, and f denotes a frequency existing when the reference clock signal input to the local crystal oscillator through the external clock interface has no frequency offset; and performing, according to EXT_CAL, external calibration on the frequency offset of the clock signal output by the local crystal oscillator. calculating an external calibration value EXT_CAL according to a first count value X on a first counter and a first reference value X 0, wherein X denotes a count value obtained, when a reference clock signal input to the local crystal oscillator through an external clock interface has no frequency offset, by the first counter by counting rising edges of the clock signal output by the local crystal oscillator, X 0 denotes a count value obtained, when the clock signal output by the local crystal oscillator has no frequency offset and the reference clock signal input to the local crystal oscillator through the external clock interface has no frequency offset, by the first counter by counting the rising edges of the clock signal output by the local crystal oscillator, and X 0 = A × f 0 f, wherein A is a first preset count value, A is determined according to required precision of calibration performed on the frequency offset of the clock signal output by the local crystal oscillator, f 0 denotes a frequency existing when the clock signal output by the local crystal oscillator has no frequency offset, and f denotes a frequency existing when the reference clock signal input to the local crystal oscillator through the external clock interface has no frequency offset; and performing, according to EXT_CAL, external calibration on the frequency offset of the clock signal output by the local crystal oscillator.