Recently, the molecular cation PtH+ was suggested as a promising candidate for the experimental search for the electron electric dipole moment. For estimating the sensitivity of the experiment on the cation and for interpretation of the experimental results, it is necessary to calculate an effective electric field acting on the electron with good accuracy because the value of the field cannot be obtained experimentally. We have performed relativistic correlation calculations to compute this effective field for the Δ3 3 electronic state of PtH+ as well as spectroscopic properties of four lowest lying states, which are also not measured up to date. The Δ3 3 state is found to be the ground one and Σ1 + state is the first excited one. The calculated value of the effective electric field acting on an electron is found to be 28 GV/cm.