To deal with the Hamiltonian model in InAs QDs with a single electron, we’ve taken the SO interaction as a perturbation term, calculated the SO matrix elements under Fock-Darwin eigenfunction which are used for second order corrections on the energies and wave functions, and considered the influence of new energy levels on g factor and effective mass m*. The expression of phonon-assisted electron spin relaxation rate Γ in InAs QDs is deduced, which shows different dependences on confined potential frequency ω0, temperature T, vertical height z0 and magnetic field B. Among them, temperature for the electron spin relaxation plays a dominant role, followed by lateral confinement potential frequency, magnetic field and the vertical height, in order of importance. (1) Growth of ω0, which corresponds to the decrease of the effective transverse size d in InAs QDs, suppresses the increase of the rate Γ. (2) The temperature T affects the rate Γ evidently, which will reduce the inhibition of ω0 on Γ. With increase of the temperature from 1 K to 7 K, the spin inversion relaxation rate grows explosively from 103 s－1 to 108 s－1. (3) The rate Γ decreases with the growth of the vertical height z0 and have the order of magnitude 100－103 s-1 at T=1 K, whereas the influence of the temperature increase (at T=6 K) on the rate will gradually exceed that of the height growth. (4) At different frequencies ω0 all curves of the rate Γ versus magnetic field B have a peak that almost appears at the same field, which is attributed to the contribution of the Zeeman term H ^ Z exceeding that of H ^ SO since there is a considerable g factor in InAs material.