The invention discloses a miniature narrow-band filter for multistage filtering, comprising an input collimator, a first-stage filter, an FP (Fabry-Perot) cavity and an output collimator, wherein theinput collimator is used for performing beam expansion on an input optical signal and then transmitting the optical signal into the first-stage filter through a free space; the first-stage filter is used for performing first-stage filtering on the optical signal transmitted by the input collimator and then transmitting the optical signal into the FP cavity through the free space; the FP cavity isused for performing narrow-band filtering on the optical signal filtered by the first-stage filter and then transmitting the optical signal to the output collimator through the free space; and the output collimator is used for receiving the optical signal which is transmitted by the FP cavity after being subjected to narrow-band filtering, and performing coupling and output on the optical signal.According to the miniature narrow-band filter of the invention, the first-stage filter is combined with the FP cavity, so that an application bottleneck of evenly spaced comb-shaped waveforms of an FPcavity filter can be solved, and narrow-band filtering in a large spectral range can be achieved; at the same time, control on a working temperature is achieved based on a thermistor and a semiconductor cooler TEC, thereby improving reliability of the filter.