Abstract: The potential energy curves (PEC) of eleven electronic states of the Sn₂ molecule were studied using the internally contracted multireference configuration interaction (icMRCI) theory. The largest relativistic pseudopotential correlation-consistent quintuple basis set augmented with diffuse functions was used. The spectroscopic parameters R_e, ω_e, ω_ex_e, ω_ey_e, B_e, α_e, β_eand T_eof ten bound states were determined. These spectroscopic parameters were in agreement with the available experiments. Based on the PECs obtained, the whole vibration-rotation energy levels were calculated by numerically solving the radical Schrdinger equation of nuclear notion. The vibration energy levels, inertial rotation and centrifugal distortion constants for each vibrational states were computed when J = 0. In the range of 10 000~24 000 cm^－1, there are eight triplet bound states are found firstly.