Poor resolution and lower modulation thansfer function(MTF) value in infrared imaging system have been remaining for many years because of its large Airy disc of optical lens and the small fillfactor of focal plane array(FPA), respectively. This paper reported a popular way to improve the resolution and MTF of infrared images using microscanning technique. The principles were briefly described. The designing rotary IR microscanner was discussed. The rotary microscanner imaging system using a 240320 pixels αsiuncooled FPA, and got higher resolution and MTF value of IR videos obviously.