The invention relates to the technical field of domestic leakage protectors, in particular to a connecting method for cutting off power supply in case of water flowing. According to the connecting method, an intelligent electric leakage protection plug, a function expansion module, a water flow sensor, a power supply system of the function expansion module and an electric water heater are arranged, wherein the intelligent electric leakage protection plug and the function extension module are in communication connection. The connecting method for cutting off the power supply in case of water flowing has the beneficial effects that potential safety hazards in the using process are avoided, the safety degree is equivalent to that of using water heater after a power plug is pulled out, and the protection mode of a leakage protector upgrades to an active protection mode from a passive protection mode.