The invention relates to a fingerprint collection methods and high-definition thin fingerprint collector, in order to solve the problem of small acquisition and poor definition in existing technology, its method is: the light source is irradiated to the prism bottom through the prism, the fingerprint under the prism bottom reflect to reflection the prism oblique of the lumbar reflection mirror and black-paint layer on the prism bottom, the fingerprint images on reflective mirror and black paint layer project on the photoelectric detector through the back of prism and the projection lens. Collector is composed of the light source, bottom longitudinal cross section of the greater than high right angle trapezoidal prism, lens and photo-electric detector; lens and photo-electric detector configurating in the back-side of prism, the ramp lumbar of prism having a reflector surface, a viewfinder with oblique configuration on the lateral of lens, the photoelectric detector above viewfinder, its characteristic is that the bottom of the prism is painted black, black paint layer and reflector mirror as a reflector surface. The method has the advantages of a biger fingerprint reflector, a greater acquisition area and high definition. Collector of small size, light weight, big area of collected fingerprint image, high clarity, collector and prism to achieve ultra-thin, is convenient to match with mouse, keyboard, door locks, cars, drive, mobile phone and other equipments of space-constrained installation for use.