Abstract: In order to control Leymus secalinus in Rheum officinale Baill. field efficiently and decrease consumption of soil water and nutrient, the biological characteristics, harm, prevention and cure of L. secalinus have been investigated and analyzed. As a result, it was indicated that the L. secalinus was 45~120 cm in height, exhibited the growth in single or cluster, and expanded its roots transversely in the soil layer of 30~50 cm. In the 50 cm plough layer per m2 area, the total rootstalk weight of L. secalinus was 1129.3 g , and the total rootstalk length of L. secalinus was 2783.3 cm, and the total fresh bud of rootstalk was 589.7, all which caused soil water-absent and fertility-deficient. When the soil water was about 13.4%, L. secalinus seedlings came out normally but their development was affected greatly. When air temperature was -6~6℃, L. secalinus rootstalks sprouted from soil, which was up to top stage in the first ten days of April, and the average seed number of individual plant was 68.4. When the number of L. secalinus in R. officinale Baill. field was 120~160 per m2, the loss of rhubarb yield was 15.8%~17.8%. When the number of L. secalinus was one per m2, manual work or mechanic and deep plough was employed to pick out the down-ground rootstalks in order to alleviate the next year’s harm. When the density of L. secalinus was high, 10% Glyphosate 22.5~30.0 kg/hm2 was adopted and distributed uniformly with the coverage of R. officinale Baill. seedlings by plastics film during the 1~3 leaf-stage of L. secalinus, and the prevention and cure rate was up to 98%. The prevention and cure of L. secalinus of the ridge field was emphasized to switch off the spread of L. secalinus of the ridge field effectively. However, it is favorable and important that the environment of agricultural field was not polluted and the persistent and steady development of Chinese rhubarb R. officinale Baill. was presented.