Abstract: The weaning ages are closely related to the growth of piglets and performance of sows. The paper reviewed the effects of different weaning ages on the growth, behavior, digestive physiology and immune function of piglets and the reproductive performance of the sows from the national and international research work. Effects of early-weaned technology on improving the sow performance and equipment efficiency, reducing feed consumption and increasing the benefit of pig production were analyzed. And besides, possible negative effects of early-weaned stress on the production of piglets, and the main problems in related research and technological application were also stated. Finally, some problems which need to be resolved for applying the early-weaned technology in intensive pig production and future research topics were discussed.