The invention discloses a method for preventing crush of a lost foam casting product, comprising the following steps of: manufacturing a foam model, brushing coating, drying, carrying out embedded box molding, pumping vacuum and casing under negative pressure in a vacuum foam lost foam casting technology, wherein a step of burning the foam model is added in the process of pumping vacuum before casing under negative pressure to burn off the foam model; a casing cavity is formed in the original space of the foam model; then, molten metal is poured in a vacuum pumping state; a gate for burning the model is reserved on the foam model; and the thickness of the coating on the model exceeds 2mm, the pouring time ranges from 70 to 120 seconds, the pouring temperature ranges from 1600 DEG C to 1750 DEG C, and the time of burning the model is not more than 10 minutes. The invention solves the problem of crush in the pouring process of the lost foam casting and can also reduce the problems of carbon pickup and carbon deposition and defects of adhesive sand, air holes, entrapped slag, and the like.