As for shallow tunnels through the rock layers, the stability of the overburden rock has a decisive role on the tunnel stability; furthermore, analyzing the stability of the overburden rock is very important to the supporting design and the choice of excavation method. Method of elastic foundation beam is used to research the moment of overburden rock, and the formula of overburden rock stable thickness is finished. Seven sections of JIAOZHOU Bay Subsea Tunnel are took for example to analyze the safety factor of different span and overburden rock thickness, then the stability of overburden rock is analyzed. The results show that the overburden rock safety factors of these seven sections of JIAOZHOU Bay Subsea Tunnel are range from 0.65 to 0.85. Compared with the experimental results, theoretical analysis of the results are more consistent The actual example verifies that the overburden rock stability in this paper is feasible.