The effects of different dosage of Bacillus amyloliquefaciens microbial inoculum on the growth and development of organic Lycium barbarum L. and soil properties in Qaidam area were studied，in order to determine the reasonable dosage and provide scientific basis for soil fertilization and organic Lycium barbarum L. production increase in this area. “Ningqi No.7” in Nuomuhong experimental area was used as the test material，and five dosage levels(29.70，44.55，59.40，74.25 and 98.10 kg·hm-2)were set up，with no application of Bacillus amyloliquefaciens as the control(CK). Compared with CK，the application of Bacillus amyloliquefaciens microbial inoculum promoted the growth of Lycium barbarum L. . The plant height，crown width，ground diameter，fruiting branch length，leaf area and SPAD value of Lycium barbarum L. were increased obviously. LN3(59.40 kg·hm-2)had the best growth promoting effect. The application of Bacillus amyloliquefaciens significantly enhanced the photosynthesis of Lycium barbarum L. ，and its intercellular CO₂ concentration，net photosynthetic rate，transpiration rate，stomatal conductance and water use efficiency were all significantly enhanced compared with those of the CK，with LN3 being the best treatment. The application of Bacillus amyloliquefaciens promoted the accumulation of soil nutrient content. Compared with CK，it effectively reduced the pH value and electrical conductivity of soil，and increased the contents of organic matter，available phosphorus，available potassium and alkali-hydrolyzable nitrogen in soil. LN3 treatment had the most obvious effect on soil improvement with the best soil fertility. After the soil fertility was improved，the yield was further increased，and LN4 treatment(74.25 kg·hm-2)had the best effect，the yield was increased by 28.73%，compared with CK. The application of Bacillus amyloliquefaciens also improved the fruit quality. The contents of Lycium barbarum L. polysaccharides，flavonoids，betaine，carotenoids，ascorbic acid and polyphenols in Lycium barbarum L. fruits were significantly higher than those of CK，and the treatment of LN3 had the best effect. According to comprehensive analysis，the growth of organic Lycium barbarum L. was improved to some extent under different dosage of Bacillus amyloliquefaciens microbial inoculum，but excessive dosage could inhibit growth，and the application of Bacillus amyloliquefaciens microbial inoculum of 59.40 kg·hm-2 had the best effect.