The invention discloses a high molecular weight polyethylene fiber and a preparation method. The method is characterized in that high molecular weight polyethylene, an anti-oxidant, a stabilizing agent, a flow modifier and an processing auxiliary agent are uniformly mixed, melt spinning and drawing are carried out, wherein the processing auxiliary agent is selected from fluorine containing-polymer processing auxiliary agent and/or polycaprolactone; the flow modifier is selected from one or more ethylene bis stearamide, methyl silicone oil, polysiloxanes and paraffin, the viscosity-average molecular weight of the high molecular weight polyethylene is 5 hundred of thousand to 150 1.5 million, and the molecular weight distribution is 3.5-5.5, the tensile strength is more than 15MPa, and the fracture percentage elongation is more than 300%. The prepared high molecular weight polyethylene fiber has high tensile strength and smooth, and the breaking strength can reach 10-20cN/dtex. The invention also discloses an application of the high molecular weight polyethylene fiber.