Abstract: In this paper, made bacterial strain Klebsiella variicola SH-1 which was selected before as material, explored colonization trends of Klebsiella variicola SH-1 on Dendrobium alternaria by rifampicin labeling, and then potting and greenhouse trials were conducted to discuss its control efficiency for Dendrobium alternaria. The results showed that SH-1 could colonize in Dendrobium, and the colonization trended to increase firstly and then decrease. After inoculation, colonization quantity reached the highest at 11d, 15d and 20d, in roots, stems and leaves respectively, and then followed by a downward trend. Kept the relatively stable colonization level in Dendrobium, with 43×104CFU/g, 232×104CFU/g and 184×104CFU/g in roots, stems and leaves after 35d, respectively. The result of potted tests on prevention of the Dendrobium alternaria showed that SH-1 had obvious control effect on Dendrobium alternaria, the control effect was the same as conventional medicine Dimetachlone that the relative control effect reached 72%, which could reach 7153%.