The present invention relates to a processing method of maca and particularly relates to an extraction method of maca crude proteins. The extraction method comprises the following steps: ultrafine grinding, alkali dissolving, ultrasonic extracting, centrifugal separating and filtering. In order to overcome the disadvantages that a traditional alkali dissolving and acid precipitating method is long in extraction time and relatively high in extraction temperature, seriously destroys proteins, and is large in energy consumption, the ultrasonic extraction technology is introduced in the method, and the ultrasonic wave is applied to the medium, so that strong tensile stress appears in an extract to form a negative pressure, which forces the raw material cell walls to be ruptured instantly, accelerates dissolution and diffusion efficiencies of the intracellular proteins in the extract, and thereby can effectively shorten the extraction time and increase the extraction rate. The method has the advantages of being simple in operation, easy to control, low in cost, good in extraction effect, large-scale in production, etc. By using the method, the maca crude protein extraction rate is 10%-14%.