Composite atomic clock

The invention discloses a combined type atomic clock, which comprises a light source 201, an atomic resonance absorption module 202, a constant temperature module 203, an optical detection unit 204, a magnetic field control module 205, a microwave radio frequency source 206 and a central processor 207, wherein the atomic resonance absorption module 202 is connected with the light source 201, the constant temperature module 203, the optical detection unit 204 and the magnetic field control module 205 in sequence; the optical detection unit 204 is connected with the atomic resonance absorption module 202; and the central processor 202 is connected with the optical detection unit 204, the magnetic field control module 205 and the constant temperature module 203 in sequence. Gas M, gas N and gas P are filled in a resonance absorption bubble, and the proportion of the three gases is controlled, so that total gas pressure coefficient inside the resonance absorption bubble is close to 0, total gas temperature coefficient is close to 0 or equal to 0, and pressure frequency shift or temperature coefficient frequency shift is overcome. Simultaneously, the combined type atomic clock has the characteristics of being simple in structure and high in accuracy degree.