The invention discloses a polyether polyurethane raw solution containing biomass powder, and a preparation method and an application thereof. The polyether polyurethane raw solution containing the biomass powder comprises a mixture component of polyether polyol containing biomass powder and an isocyanate prepolymer component, and the mixture component of polyether polyol containing the biomass powder includes polyether polyol, a chain extender, the biomass powder and a physical property enhancer; the physical property enhancer is one or more of diol amine containing a long-chain alkyl branchedchain or long-carbon-chain monool. The reuse problem of the biomass powder is effectively solved, the appearance of polyurethane flexible foams is improved, and diol amine containing the long-chain alkyl branched chain and long-carbon-chain monool with a straight-chain linear structure are complexed as the physical property enhancer, and physical property improvement effect for the polyurethane flexible foams containing the biomass powder is more obvious.