The invention discloses an enhancing viscosity technique of galactomannan endosperm split, which uses galactomannan as raw material, and prepares vegetable gum powder through the steps of hydration, extrusion, drying and pulverization. Compared with tradition direct pulverization technique, the technique has almost same pulverize, does not increase product cost, but the 1% of viscosity of galactomannan which is treated by the technique is increased over 50% than the original gum, reduces over 10% water insoluble material, and quality of product is increased greatly, and the product can add value over 30%.