A scheme is proposed to implement quantum controlled-not (CNOT) gates with a resonant cavity and this quantum gate is used to carry out teleportation of an arbitrary single-atom superposition state. By using three level atoms, it can be realized through single-qubit operation and resonant interaction between two atoms and a resonant cavity. The interaction time between two atoms and the single-mode cavity is very short, which is important in view of decoherence. This character is one of the advantages of this scheme comparing to the scheme based on detuned cavity.