Dendrobium Nobile oligosaccharide was extracted in water and purified by a three-step process: precipitation of protein and polysaccharides by anhydrous ethanol, decolorization after precipitation with macroporous resin and final purification through Sephadex G-25 gel chromatography. As a result, a resultant oligosaccharide compound was obtained, and its effect on growth curve, heat resistance and anti-phenol inhibition of Lactobacilli in a stress environment was further studied. The results showed that the oligosaccharide significantly promoted the growth of Lactobacilli, and reduced the damage caused by high temperature and phenol.