The hydrogen abstraction reaction AsH3 + H --> AsH2 + H-2 has been studied by direct dynamics method. The potential energy surface information is obtained at the UQCISD/6-311 + G** level of theory. Energies along the minimum energy path are improved by G2//QCISD calculations. The reaction thermal rate constants for the temperature range 200-1600 K are calculated by CVT/SCT method. The results show that the variational effect is small and in the lower temperature range, the small curvature effect is important for the title reaction. Good agreement with experimental values is found for the rate constants over the measured temperature range.