In A(BB0.51B0.52)O3 perovskite-like ferroelectrics. besides the stable 1/2〈lll〉-typeordered structure, two new kinds oi ordered structures, 1/2〈110〉 and 1/2〈100〉 superlattices, have been observed at room temperature and -150℃ respectively. In this paper, the longrange interactions are introduced into the eight-point cluster variation method to analyse the stabilities of the three kinds of ordered structures. The results are in good agreement with experimental observations.