Impact aging experiment based on the tolerance of MOV(Metal Oxide Varistor) under continuous Power Frequency overvoltage was designed to solve the problem that the change of breakdown voltage is too small to tell the aging degree of MOV chip. Different situations of Impact aging and the tolerance of MOV under different amplitude of overvoltage were studied, the relationship between the internal current during the tolerance (Iin) and the time is given. Experimental result was studied with Dual Schottky barrier theory and Voronoi grid model. The result shows that the larger the aging degree impacted by 8／20μs current pulse is ,the larger the initial value of Iin is; The increased rate of over time is proportional to the initial aging degree; the tolerance time is inversely proportional to the aging degree of MOV chip; the larger the amplitude of overvoltage is, the shorter the tolerance time is when the aging situations are equal. These results can be used to determine the Aging and deterioration degree of the MOV chips.