In this paper, we mainly study the stability of iterated polynomials and linear transformations preserving the strong q-log-convexity of polynomials Let [T n,k ] n,k≥0 be an array of nonnegative numbers. We give some criteria for the linear transformationpreserving the strong q-log-convexity (resp. log-convexity). As applications, we derive that some linear transformations (for instance, the Stirling transformations of two kinds, the Jacobi-Stirling transformations of two kinds, the Legendre-Stirling transformations of two kinds, the central factorial transformations, and so on) preserve the strong q-log-convexity (resp. log-convexity) in a unified manner. In particular, we confirm a conjecture of Lin and Zeng, and extend some results of Chen et al., and Zhu for strong q-log-convexity of polynomials, and some results of Liu and Wang for transformations preserving the log-convexity.The stability property of iterated polynomials implies the q-log-convexity. By applying the method of interlacing of zeros, we also present two criteria for the stability of the iterated Sturm sequences and q-log-convexity of polynomials. As consequences, we get the stabilities of iterated Eulerian polynomials of type A and B, and their q-analogs. In addition, we also prove that the generating functions of alternating runs of type A and B, the longest alternating subsequence and up-down runs of permutations form a q-log-convex sequence, respectively.MSC: 05A20, 11B68