The present invention discloses a preparation method for a natural building material sealant, and belongs to the technical field of sealant preparation. The method disclosed by the present invention is characterized by comprising the steps of taking honey, maple tree sap and peach tree sap as raw materials; removing water in the honey to crystallize the honey into crystals; mixing the air-dried maple tree sap and the air-dried peach tree sap with the crystal honey to obtain a mixture; heating the mixture at certain temperature to make the mixture completely dissolved; adding sulfur at a certain rotating speed and temperature into the dissolved mixture and carrying out blending; and performing fluidization with a fluidized bed, thereby obtaining the natural building material sealant. Accordingly, the purpose of improving the water resistance and the curing rate of the sealant can be achieved. The preparation method has the beneficial effects that: the preparation method is simple; no primer is needed during utilization of the sealant; the sealant is not prone to foam in high temperature and high humidity environments; the utilization effect is good; and the obtained sealant is good in water resistance, fast in curing speed, good in adhesion, and is prone to aging due to UV light.