The invention relates to the technical field of production of amine-terminated polyether, in particular to a preparation method of monoamino polyoxyethylene ether. The invention relates to the preparation method of monoamino polyoxyethylene ether. The method comprises the following steps: reacting N-(tert-butyloxycarbonyl) ethanolamine with a supported catalyst SnO2-PtO2-Al2O3 to obtain 2-(Boc amino) ethanol polyoxyethylene ether through a polymerization reaction, directly adding an end-capping reagent after the reaction is finished, allowing a by-product HCl in the reaction to directly reactwith a BOC group to generate isobutene, CO2 and amino-terminated polyether salt, and finally obtaining the product monoamino polyoxyethylene ether by adjusting the pH value.