To explore the evolution law of crack initiation resistance (CR) in ZnO·Al2O3·nSiO2 (n=2, 2.35, 2.5, 2.65, 3, 3.5) glasses varies with SiO2 content, series of glass samples were prepared by the conventional meltquenching method. By characterizing CR and the microstructure of these aluminosilicate glasses in detail, the results shows that an abnormal evolution that CR increases first and then decreases with the increase of SiO2 content， and arrives the maximum value of 31.1 N at n=2.5. With the increase of n: (1) the atomic packing density decreases gradually, which induces the increase in CR due to the increase in volume available for densification; (2) the quantity of Al—O polyhedra decreases, which leads to the drop in CR due to the higher damage resistance of Al—O polyhedra compared to the SiO4 units; (3) considering the strong retarding upon crack initiation originated from phase interfaces, the nonmonotonic change in the quantity of phase interfaces induces the corresponding abnormal evolution in CR for the aluminosilicate glasses. The competition and synergy of the above three factors are the structural origin of the abnormal evolution of CR in this system. Finally, considering the insignificant change in composition near the maximum value, the nonmonotonic change in the quantity of phase interfaces varies with n should be the main structual origin of the abnormal evolution in CR.