An ab initio potential energy surface (PES) for the ground state (12A′) of the chemical reaction Ar+H2+→ArH + +H has been constructed from a set of accurate ab initio data, which we have computed using the coupled-cluster theory including all single and double excitations plus perturbative corrections for the triples UCCSD(T) with a large orbital basis set of aug-cc-pV5Z. The new PES has a root-mean-square (rms) error of 0.5341kcal/mol. The total integral reaction cross-sections have been calculated at three collision energies by means of the quasi-classical trajectory (QCT) calculation based on the new PES and compared with previous TSH results.