The potential energy curve (PEC) of ground X2Π state of PS radical is studied using highly accurate internally contracted multireference configuration interaction approach with the Davidson modification. The Dunning’s correlation-consistent basis sets are used for the present study.To improve the quality of PECs, scalar relativistic and core-valence correlation corrections are considered. Scalar relativistic correction calculations are performed using the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. Core-valence correlation corrections are calculated with an aug-cc-pCV5Z basis set. All the PECs are extrapolated to the complete basis set limit. Using the PEC, the spectroscopic parameters (Re, ωe, ωexe, ωeye, Be, αe and De) of the X2Π state of PS are determined and compared with those reported in the literature. With the Breit-Pauli operator, the PECs of two Ω states of the ground Λ-S state are calculated. Based on these PECs, the spectroscopic parameters (Te, Re, ωe, ωexe, ωeye, Be and αe) of two Ω states of PS are obtained. Compared with those reported in the literature, the present results are accurate. The vibration manifolds are evaluated for each Ω and Λ-S state of non-rotation PS radical by numerically solving the radical Schrödinger equation of nuclear motion. For each vibrational state, the vibrational level and inertial rotation constants are obtained, which are in excellent accordance with the experimental findings.