The invention discloses a preparation method of functional white carbon black for a green tire. Sodium silicate and sulphuric acid are used for reaction; aging slurry is obtained through modificationby sulfydryl silane coupling agents; then, press filtering, washing, pulp preparation and centrifugation spray drying are performed to prepare the functional white carbon black for the green tire. Inthe reaction process, the sulphuric acid with the mass percentage being 22 to 25 percent is added at a uniform speed; stirring is performed; after the sodium silicate solution reacts to a condition that the pH is 4.5 to 5.0, aging is performed; the sulfydryl silane coupling agents are added according to the quantity of 5 to 10 percent of the volume of the aging slurry. The prepared functional white carbon black for the green tire has the advantages that a tire product has low rolling resistance, high operation and control performance and good wear-resistant performance, so that the tire is safer and achieves better environment-friendly performance; the energy is saved; durability is high.