The invention discloses an extraction preparation method and device of polyoxymethylene dimethyl ether reaction raw materials. The device comprises a preheater I, a preheater II, an extraction tower, a dehydrating tower, a distillation tower, a fan and a material intermediate tank, wherein the extraction tower, the dehydrating tower, the distillation tower, the fan and the material intermediate tank are sequentially connected, the preheater I and the preheater II are connected with a liquid inlet of the extraction tower, and a discharging outlet of the material intermediate tank is connected with a device for performing a polymerization reaction externally. According to the method, a cheap formalin sold in the market is subjected to formaldehyde concentration and dehydration through physical extraction and decompression rectification methods, distillation is performed through formaldehyde in an extracting agent for preparing pure formaldehyde gas almost containing no water, the formaldehyde gas is pressurized by pressurizing the fan and dissolved into a working solution forcibly, effective separation of the formaldehyde and the extraction agent is ensured, the working solution absorbing the formaldehyde is the raw material for preparing polyoxymethylene dimethyl ether, and multiple purposes are achieved at a time.