Any quantum computation can be simplified to a gate sequence. But the quantum computation is carried out by a certain physical system. We propose here a scheme to carry out two-atom quantum controlled phase gate through cavity QED. In our scheme,the atomic transition is largely detuned with the cavity mode of interest,so the atomic spontaneous emission loss is strongly suppressed,and this leads to the enhancement of probability of gate operation. But fidelity is decided by constants α,β,γ,The numerical calculation based on current experimental technology shows that our scheme has high gate fidelity,the average value of fidelity ■=0.982318.That scheme can be realized by experiment.