Abstract: The experiments were conducted to study the microclimate environment of two intensive weaning houses and observe the behaviour of the weaning piglets in the summer. The results showed that the weaning houses could provide a good microclimate condition for the piglets. But it was also showed that the weaning piglets could not fulfill the natural instincts and behavioural needs because of the barren rearing environment, such as less available space and lacking of effective stimulator. The piglets tended to spend more time in lying. As the sleeping area was not comfortable, the aberrant lying pattern like lying on belly, bunching up and piling on top of each other were observed. These actions will result in quality decrease of sleeping and therefore affect the pig production.