When the coupling power transfer ( CPT) is applied in the submerged buoy system, it can provide power for the communication beacon without electrical contact. However, the distance between the beacon and the submerged buoy will change. The system may be in the deviating resonance state and its efficiency will be reduced. In this article, the law of the coupling coil with the distance is analyzed. The model of the CPT system is formulated. The relationship between the coil efficiency and frequency in the deviating resonance state is studied. The system efficiency can be improved by using the search algorithm, which is evaluated by simulation. A prototype of the CPT system with variable distance is established to evaluate the search algorithm. Experimental results show that the search algorithm can improve the system efficiency under the change of the coil distance. Compared with the fixed-step perturbation observation algorithm, the maximum efficiency of the particle swarm optimization (PSO) is increased by 3% , which is less affected by the choice of the initial center frequency. The efficiency of the CPT system can be improved when the coil distance changes by using PSO.