The typical test cases have been performed to assess the performance of the improved configuration-based multi-reference second order perturbation theory (CB-MRPT2).The test cases include double-bond breaking reactions for the X 1 ∑+g, B1△g, and B1∑+g states of C2, triple-bond breaking reaction for the X1∑+g state of N2, the singlet-triplet splitting of in CH2 and SiH2, the vertical excitation energies of ozone.