The invention discloses a nuclear cascade utilization system and method based on liquid metal self-evaporating magnetic fluid power generation, and belongs to the field of comprehensive nuclear energy utilization. The system is mainly composed of a magnetic fluid pump, a magnetic fluid power generation channel, a fan, a nuclear reactor heat source, an electrolytic water hydrogen production device and related heat exchangers. Liquid metal is heated by the nuclear reactor heat source to vaporize partially and generate bubbles, resulting in volume expansion to push the liquid metal to flow by the power generation channel. Magnetic induction lines are cut to generate induced electromotive force, and then condensation is conducted by a condenser. The magnetic fluid pump pumps the liquid metal into a liquid metal heat evaporator to complete the circulation. Generated electrical energy can be used partially or totally for hydrogen production. Through related heat exchangers and processes, the resulting hot water can be used as domestic hot water. The system provided in the invention is simple and compact, the cost is low and the stability is high. The invention also provides an advanced method, for nuclear energy cascade utilization, which can realize power generation, hydrogen production and heating at the same time.