This invention has disclosed a manufacturing method for polypentenyl phosphate. Put oil of plant polyprenol into nonpolar organic solvent, formed a mix solution, under the nitric organic alkali catalysis, put phosphorylation agent into above-mentioned mix solution, mix, get mixture contained reaction products, put hydrolysis liquid into the mixture, mixing for 1-2 hours, then evaporation, retrieve the organic solvent, the hangover is mainly emulsion of polypentenyl phosphate. Extract above-mentioned emulsion with the solvent to separate, volume ratio of emulsion and solvent is 1:(5-100), the solvent is mixture of nonpolar organic solvent and water, ratio of nonpolar organic solvent and water is (1-10):1, mixing for 1-10 hours, then wait 1-10 hours quietly for delamination, wash the supernatant with saturated inorganic sodium salt solution again and again to neutrality, recovery nonpolar organic solvent in the supernatant, gained yellow oil of polypentenyl phosphate.