The invention provides a method for inactivating enzyme of longan pulp by steam blanching. The method adopts fresh longan as a raw material, and the longan pulp which can still keep the fresh fragrance and the original color of the longan can be obtained by processing the raw material by the sequential working procedures of cleaning the longan, peeling the shell, removing the core, inactivating the enzyme by steam blanching, cooling, etc. The method avoids the enzymatic browning caused by an endogenous enzyme system, and prevents the longan pulp from directly contacting water, thereby reducing the loss of water-soluble matters; and the hypobaric hypoxia environment caused by the steam is in favor of the maintenance of the natural color and the flavor of the longan pulp, thereby preventing the raw and boiling taste from being generated in the operation of processing the longan pulp.