The potential energy curves (PECs) of the PH (X3-, a1 and A3) are investigated by the highly accurate valence internally contracted multireference configuration interaction (MRCI) method and the MRCI method including the Davidson modification (+Q) in combination with the correlation-consistent basis sets, aug-cc-pV5Z. With these PECs obtained here, the spectroscopic parameters of three isotopologues, PH (X3-, a1 and A3), PD (X3-, a1 and A3) and PT (X3-, a1 and A3), are determined. These parameters are compared in detail with those previously reported in the literature, and agreement is found between the present results and the experimental data. The values of vibrational level G(), inertial rotation constant B and centrifugal distortion constant B for the first 12 vibrational levels of PH (X3 -), PD (X3 -) and PT (X3 -), are calculated when the rotational quantum number J equals zero, which are in agreement with the available measurements. Comparison with the available experimental data shows that the present molecular constants are accurate.