The invention discloses a tambac inducer and a preparation method thereof. The tambac inducer comprises an aquilaria sinensis tree vivo stem, a PDA culture medium, a potato sucrose culture medium and an aquilaria sinensis matrix. The method comprises the following steps of cutting off a part of an aquilaria sinensis tree vivo stem, which is forming tambac, and sterilizing, culturing, separating and identifying to obtain a tambac inducible strain; activating the strain by the PDA culture medium and fermenting by the potato sucrose liquid culture medium, and then inoculating the strain to the aquilaria sinensis matrix, and culturing for 3-5 days under the conditions of constant temperature of 30 DEG C, darkness and ventilation, thus obtain the tambac inducer. The invention has simple method, can remarkably shorten the forming time of the tambac, enhance the cultivating benefit of aquilaria sinensis trees and has favorable market application prospect.