The invention relates to a method for removing aldehydes in an epoxypropane reaction mixture. The method comprises carrying out primary aldehyde removal on an epoxypropane reaction mixture through an aldehyde-free resin tank so that aldehyde content is reduced and epoxypropane product purity is guaranteed, orderly removing water and unreacted propylene, feeding the materials containing epoxypropane and methanol into an epoxypropane refining tower, carrying out extraction on methanol in the middle section of the tower through desalinized water containing ethanolamine or hydrazine hydrate, simultaneously removing residual aldehyde in the epoxypropane product, separating the separated aqueous solution through a methanol tower, feeding the aqueous solution into a membrane separation device, further removing residual aldehydes and impurities, returning the methanol as circulation methanol at a penetration side to a reaction system and returning aldehyde-containing methanol at a retentate side to a collection tank. The method utilizes less devices, reduces a disposable investment, does not need hydrogen in a separation and recovery process, does not increase a safety risk, is safe and reliable in use and reduces later waste water treatment energy consumption.