The invention discloses a preparation method for a polyurethane-photochromic microcapsule. The preparation method comprises the following steps: dissolving an azo compound in butyl acetate, carrying out homogenization, then successively adding 4,4'-diphenylmethane diisocyanate, polyethylene glycol 400 and stannous octoate, and carrying out a reaction under stirring so as to obtain a performed polymer; weighing proper amounts of hydroquinone dihydroxyethyl ether and 1,3-butanediol, adding hydroquinone dihydroxyethyl ether and 1,3-butanediol into a performed polymer solution, and carrying out stirring so as to form a polyurethane capsule wall; and carrying out centrifugal separation, carrying out washing with an ethanol solution with a concentration of 30%, and carrying out drying so as to obtain the polyurethane-photochromic microcapsule. The method provided by the invention has simple operation, short synthesis time and high coating rate; the obtained microcapsule has uniform particle size, wherein the average particle size is about 0.6 [mu]m; meanwhile, the polyurethane-photochromic microcapsule is free of formaldehyde, so the safety is guaranteed.