Let \(\overline{p}(n)\) denote the number of overpartitions of n. In this paper, we establish the generating function for \(\overline{p}(96n+12)\) modulo 81 using elementary dissection techniques and theta function identities. Based on this generating function and some identities of Ramanujan theta functions \(\psi (q)\) and \(\varphi (-q)\) , we obtain a congruence relation and an infinite family of congruences modulo 81 for \(\overline{p}(n)\) . Furthermore, by studying the periodicity of \(\psi (q)\) based on the \(\ell \) -dissection formula of \(\psi (q)\) given by Cui and Gu, we find some arithmetic relations and infinite families of congruences modulo 3 and 27 for \(\overline{p}(n)\) .