The invention provides a method for preparing high-grade sucrose fatty acid ester from woody oil, comprising the following steps of: mixing woody oil, lower alcohol and an aqueous sodium hydroxide solution for reacting, after the reaction is ended, regulating the pH value to be faintly acid, standing for demixing, separating out a liquid at the upper layer and a hydrous crude glycerol phase at the lower layer; then mixing the liquid at the upper layer with the lower alcohol for sealing, freezing at low temperature, then filtering to obtain a clear filtrate, dissolving filter cakes, and then carrying out reduced pressure distillation to obtain a saturated fatty acid; mixing the clear filtrate with urea, heating until the mixture is dissolved, filtering after freezing at low temperature, rotatably evaporating the filtrate, then dissolving with a non-polar solvent, filtering, rotatably evaporating the filtrate to obtain polyunsaturated fatty acids; and finally, under the protection of N2, mixing the separated fat acids with sucrose, a cosolvent and a catalyst, heating for reacting, and refining the reaction mixture with a two-phase extraction method to obtain the sucrose fatty acid ester. The invention has the characteristics of easy obtaining of rich raw materials, low cost, easy separation of product, stable performance, high purify, and the like.