The present invention discloses a method for preparing an InAs room-temperature ferro magnetic semiconductor material, which comprises the following steps of: cleaning the surface of an InAs single chip with a chemical cleaning agent and removing an oxide layer and an inorganic substance on the surface by an acid etching method; putting the cleaned InAs single chip in a deposition apparatus to deposit a layer of metal diffusion layer; placing the InAs single chip deposited with the metal diffusion layer in a quartz tube, and sealing the quartz tube after vacuumizing; heating the vacuumized quartz tube in heating equipment at a constant temperature so as to speed up the diffusion process; after cutting up the heated quartz tube, taking out the InAs single chip, and etching the redundant metal with an acidic liquid; and cleaning the n InAs single chip with the chemical cleaning agent to finish the preparation. The method of the invention can prepare the ferro magnetic semiconductor material of which the temperature of the InAs single chip is over 300K; in the whole preparation process, the used equipment is mature in technology and commonly used in industry; and the method reduces the preparation cost and the preparation time and is very favorable for popularization.