The invention relates to a device and method for feeding pigs with a liquid feed. The feeding device comprises a dry feed feeding device, a water feeding device, a feeding system, a stirring and weighing system and a master control system, wherein the discharging end of the dry feed feeding device and the water inlet end of the water feeding device are connected with a stirring tank, the stirring and weighing system comprises the stirring and a weighing sensor, the feeding system comprises a pushing machine, a high-pressure eddy fan, a feeding pipeline and a four-way feeding valve, the stirring tank is communicated with a feeding port of the pushing machine, a discharging port of the pushing machine is connected with a first port of the four-way feeding valve, a second port of the four-way feeding valve is communicated with a pigsty, a third port of the four-way feeding valve is connected with the high-pressure eddy fan, a four port of the four-way feeding valve is communicated with the stirring tank, and the master control system is in controlling connection with the dry feed feeding device, the water feeding device, the feeding system and the stirring and weighing system. The feeding device can automatically perform liquid-feed feeding, saves labor, can perform accurate feeding and ensure the nutrition demand of pigs, and the problem that labor input for liquid-feed feeding is large, and meeting of the nutrition demand of pigs is not easy to determine.