In this paper, we prove the -log-convexity of Domb’s polynomials, which was conjectured by Sun in the study of series for powers of . As a result, we obtain the log-convexity of Domb’s numbers. Our proof is based on the -log-convexity of Narayana polynomials of type and a criterion for determining -log-convexity of self-reciprocal polynomials.