Abstract: Lijiang 2.4-metre telescope, as the largest general-purpose optical telescope of China currently, plays a very important role in the field of night astronomy observation. From the recent distribution time of observation, the spectrum observation of Yunnan Faint Object Spectrograph and Camera (YFOSC) accounts for the largest proportion of the total observation time. Thus improving its spectrum observation efficiency has become the key factor in ensuring the telescope's stable scientific output. This paper disusses two key factors which affect the efficiency of YFOSC spectrum observation—acquire stars into slit and close-loop guiding of telescope, and introduce the way of improving the quality and efficiency of YFOSC spectrum observation. After the actual test, it is concluded that using the new algorithm makes the accuracy of star image into slit increase by about 50%, and its time shortened by about 7 minutes; while the accuracy of telescope close-loop guiding is better than 0.5″ in 1 hour, and the offset of stars on the image plane is not more than 1.8 pixel.