Abstract: The basic influence of devitrification of silica-based ceramic core and the relation between cristobalite and core's properties have been investigated systematically in this article.Experimental results indicate, that additions and sintering temperature have evident effect on devitrification.The former car. change devitsifying temperature ,and the latter can accelerate devitrifying process.With cristobalitc crystallized,high temperature deflection decreases; considerably sintering strength and high temperature strength decrease; and linear thermal expansion increases.Through controlling devitrification of core,it is possible to make a high-quality core which is used for the prodttctioa of directionally solidified blade with complex cavities.