The invention belongs to the technical field of polyether polyol synthesis and specifically relates to a preparation method of low-molecular-weight polyether polyol for polyetheramine. According to the preparation method, 2-methyl-1,3-propylene glycol, which is used as a starting agent, reacts with epoxide in the presence of an alkali metal catalyst at low temperature; and then, the reaction product is end-capped with epoxypropane at high temperature so as to obtain low-molecular-weight polyether polyol for polyetheramine. During the polymerization, 2-methyl-1,3-propylene glycol is used as the starting agent. Due to structural regularity and symmetry of 2-methyl-1,3-propylene glycol, activities at two ends are identical. During polymerization between 2-methyl-1,3-propylene glycol and the epoxide, polyether structure is more regular. During amino-capping, activities at two ends are consistent. The product has characteristics of amorphism, strong weatherability, tension resistance, strong bending resistance and the like. By the structure, polyetheramine can be endowed with characteristics of low melting point, low viscosity and good intersolubility with auxiliaries.