The invention provides an ocean thermal energy conversion method and an ocean thermal energy conversion device. The method comprises the following steps of: heating a low-boiling-point working medium by using hot seawater on a surface of ocean; evaporating the low-boiling-point working medium; feeding into a turbine to push a turbo generator set to work for power generation; condensing working medium gas which is exhausted from the turbine into liquid by using cold seawater on a deep layer of the ocean; heating by using the hot seawater; feeding into the turbine to make the working medium gasevaporated; pushing the turbo generator set to work for the power generation; cyclically executing the steps; and continuously carrying out power generation. Power is generated by using ocean surfacewind power, a heat pump device is driven by the power, the temperature of the working medium is further raised by using a medium of the heat pump device, and the volume expansion ratio of the workingmedium is improved; and the temperature of the cold seawater is further reduced by using the medium of the heat pump device, the working medium exhausted gas is condensed by using the low-temperatureseawater, and a condensing effect of the working medium exhausted gas is improved. The method and the device improve the efficiency of closed cycle generation of ocean thermal energy conversion, realize the comprehensive utilization of ocean thermal energy and wind energy, have an important practical value, provide environment-friendly energy sources, and are easy to use and promote in large scale.