Abstract: Burner of rotary cup type is a burning instrument in most popular use in the heaters for pipleine. In spite of its numerious advantages, this type of burner has a poor performance due to its improper air feeding system. Considering its characteristics, the following three solutions are given to air feeding problems : ①to distribute and commutate the incoming air so as to achieve uniform air feeding, regular flames and stable burning; ②to speed up the air feeding at throat in order to improve the burning efficiency; ③to choose a proper subtended angle for the burner. Based on the foregoing principles, modifications are made for the air feeding system of the Heater 105, and better performances achieved.