The invention relates to a device and a method for improving an OFDR frequency domain sampling rate. The device comprises a sweep-frequency laser device, an optical fiber coupler, a measurement module, an auxiliary module, a data acquisition card, and a computer. In the measurement module, a reference arm signal and a measuring arm are subjected to beat frequency interference, and a generated beatfrequency signal is acquired by means of the data acquisition card which is controlled by means of an external clock signal generated in the auxiliary module in an equal frequency domain manner. Themethod comprises the steps of: dividing N times of sampling according to the magnitude of the measurement length, utilizing a frequency shifter for adjustment under the condition that the two arm frequency difference of an interferometer of the auxiliary module is fixed, and sequentially subjecting sampled signals to frequency translation for data acquisition; and performing FFT operation after superposing the data acquired repeatedly to obtain a finally result. The method improves the OFDR frequency domain sampling rate, is conductive to expand the OFDR measurement range, can adjust the measurement range according to user needs, is convenient, has precise results, and can meet the requirements of various measurement environments.