The invention discloses a method for increasing the resolution and sensitivity of an ion mobility spectrometer, which includes the following steps: (Step 1) a sample to be analyzed is ionized; (Step 2) frequency modulation is carried out on a continuous ion current coming from an ion source; (Step 3) under the condition of switching off drift voltage, ion gate modulation signals are continuously sent into an ion gate and a signal of a Faraday plate detector is acquired at the same time, and thereby a first average spectrogram i(t) originally outputted by the detector is obtained; and under the condition of switching on drift voltage, a second average spectrogram p(t) originally outputted by the detector is obtained; (Step 4) processing recording is carried out on the first average spectrogram i(t), so that a curve of ion strength varying along with time under different mass-to-charge ratios is obtained; (Step 5) the second average spectrogram p(t) is processed, and cross-correlation transformation is then utilized to reconstruct an ion mobility spectrometry. The method disclosed by the invention has the advantages of flexible control, high sensitivity, high resolution and simplicity.