Abstract: A lab-scale experimental setup was provided to investigate the influencing factors on the carbon output from a rotary calcining kiln, such as rotating speed, kiln slope, kiln inner diameter and height of dam at kiln tail. The results indicated that the mean residence time in kiln is shortened greatly if the rotating speed is lower than 4 r/min and shortened moderately if higher than 4 r/min, and the time is shortened as well with the increasing kiln slope and height of dam. The carbon output from the kiln increases greatly if the rotating speed is lower than 3 r/min and its increment lowers if higher than 3 r/min, and the output increases greatly with the increasing height of dam. In addition, the position where the feeding pipe is mounted in also affects obviously the output from the kiln.