Working principle: the liquid level switch is composed of magnetic reed switch and float magnetic reed switch encapsulated within the guide bar when float move up and down with the measured liquid level its internal magnets attract magnetic reed switch contact action so as to detect the liquid level position as a liquid level control and instructions. Scope of application: household appliances (such as: pure water machine water machine drinking machine humidifier dehumidifier electric water heater air conditioning equipment household water direct drinking system etc.) industrial equipment (such as: empty hydraulic press air cooler drainage device lubricating oil system) gardening equipment medical equipment beauty salon equipment aquatic farming and industrial water purification sewage treatment system automatic door control system etc.