A class of binary sequences with period pq is constructed using generalized cyclotomic classes, and their autocorrelation distribution and 2-adic complexity are determined using Gauss sum and group ring theory. The results show that the autocorrelation function of the new sequences is 3-level if p ≡ 3 (mod 4) and q ≡ 3 (mod 4) which is very close to the optimal and the 2-adic complexity of these sequences is maximum if p < q < 2p − 1. According to the rational approximation algorithm(RAA), these sequences have quite good cryptographic properties in the aspect of autocorrelation and 2-adic complexity.