The invention discloses a method for preparing 
silicone sealant. The method comprises the following steps: adding alpha,
omega-dyhydroxy 
polydimethylsiloxane, filler and dimethyl 
silicon oil into a vacuum kneading 
machine, vacuuming, heating and mixing for 2-5 hours; stopping heating, introducing 
nitrogen to change the 
vacuum state, adding a 
silane coupling agent, mixing for 0.5-1 hour at the vacuum degree of -0.06 to -0.1Mpa, introducing 
nitrogen to change the 
vacuum state; sealing and cooling to 
room temperature, subsequently transferring into a stirring 
machine, adding a cross-linking agent, a 
thickening agent and a catalyst, vacuuming, and uniformly stirring and mixing so as to obtain the 
silicone sealant. According to a product of the 
silicone sealant, the addition amount of the filler is increased, the product stability and the 
surface smoothness are improved, the 
thixotropy and the deep curing are also improved, the curing homogeneity is good, the tensile strength, the elasticity and the cohesiveness are greatly improved, expensive white 
carbon black can be replaced, the filling amount is large, the 
curing time is short, the construction efficiency is improved, the process is simple and feasible, the production cost is low, and good 
economic benefits and 
social benefits are achieved.