In this talk,I will first report our recent advances in developing electronic structure methods for strongly correlated systems,large molecules and condensed phase systems.For strongly correlated systems,we have developed two new electronic structure methods: block-correlated second-order perturbation theory with the generalized valence bond(GVB)reference(GVB-BCPT2)and a hybrid approach by combining GVB-BCPT2 with a variational method such as CASCI or DMRG.1,2 The first approach can provide reasonably accurate descriptions for simultaneous dissociations of many single bonds in some systems.