In this work, we performed a high level ab initio study on the low-lying electronic states of CSe, utilizing MRCI+Q (the internally contracted multireference configuration interaction, and Davidson's correction) method with scalar relativistic and spin orbit coupling effects taken into account. The potential energy curves of 18 Lambda-S states associated with the lowest dissociation limit of CSe molecule, as well as those of 50 Omega states generated from the Lambda-S states were computed. The spectroscopic parameters of bound states were evaluated, which agree well with existing theoretical and experimental results. With the aid of calculated spin orbit matrix elements and the Lambda-S compositional variation of the Omega states, the spin orbit perturbations of low-lying states to the A(1)Pi and a(3)Pi states are analyzed. Finally, the transition dipole moments of Ain, A(1)Pi, A'(1)Sigma(+), and a(3)Pi(1) to the ground X-1 Sigma(+) state as well as the lifetimes of the four excited states were evaluated.