1. A sectional image recognition method applied in a zonal fingerprint recognition device having a memory with small storage capacity, comprising: Step a: setting an image selection frame configured to capture a portion of a fingerprint image; Step b: capturing a fingerprint image block of the fingerprint image of a size corresponding to the image selection frame; Step c: executing a minutiae conversion program on the fingerprint image block to generate a minutiae block image corresponding to the fingerprint image block; Step d: repeating Step b and Step c until all fingerprint image blocks corresponding to the minutiae block images are obtained; Step e: executing an image stitching program on the corresponding minutiae block images according to an acquisition sequence in which the fingerprint image blocks are obtained, so as to generate an overall minutiae image corresponding to the stitched minutiae block images; Step f: executing a fingerprint recognition program on the overall minutiae image; and Step g: according to a recognition result acquired by the fingerprint recognition program, sending, by the zonal fingerprint recognition device, a corresponding response message.