The invention aims at providing a ship low-speed diesel engine waste heat comprehensive recycling system control method based on the rotation speed. An exhaust pipe of a ship low-speed diesel engine is connected with a power turbine and a turbine of a turbocharger. The turbine of the turbocharger is connected with a waste heat boiler, and the waste heat boiler is connected with a steam turbine and an organic working medium steam turbine. The power turbine, the organic working medium steam turbine and the steam turbine are connected with a power generator. The turbocharger is further connected with a bypass channel. A startup or shutdown control signal is output to a waste heat boiler control device, an organic working medium power generation unit control device, a steam turbine power generation unit control device and a power turbine power generation unit control device according to the rotation speed of the ship low-speed diesel engine so that control over startup and shutdown of the corresponding devices can be achieved. By adoption of the section control mode, different utilization measures can be adopted according to exhaust gas parameters generated when the diesel engine runs at different rotation speed sections, and the waste heat recycling efficiency is improved.