One hundred and eighty-nine endophytic bacteria strains were isolated from healthy cucumber plants collected from Hunan, Yunnan and Hainan. The inhibitory radius of strain Y-10 to Pseudomonas cichorium, the pathogen of cucumber leaf spot, was 16 mm, and the antagonistic effect was the best. The strain Y-10 was identified as Bacillus subtilis by combining the results of morphological, physiological and biochemical characteristics and 16S rDNA and rpoA genes analysis. Bacterial suspensions of strain Y-10 was diluted to 4×109, 4×108, 4×107, 2×107, 4×106, 4×105 cfu/mL by gradient dilution, and 4×108, 4×107, 4×106, 4×105 cfu/mL suspensions were selected to soak seeds separately, while 4×109, 4×108, 4×107, 2×107, 4×106 cfu/mL solutions were used to irrigate seedlings independently. Sterile water soaking and root irrigation were used as blank controls. The results show that some dilutions of strain Y-10 could promote the cucumis seedling growth and seeds germination. After soaking seeds with 4×107 cfu/mL bacterial solution, the germination rate of seeds was 6.01% higher than that of the blank control. The seeds hardly germinated when treated with 4 ×109cfu / mL bacterial solution, and the root length, root fresh weight, shoot fresh weight and shoot dry weight of cucumber seedlings increased by 40.71%, 33.59%, 35.21% and 58.18% respectively. In the treatment with 4 ×109cfu / mL bacterial solution irrigation, the root length, root fresh weight, shoot fresh weight and shoot dry weight of cucumber seedlings, compared with the blank control, were increased by 11.49%, 19.57%, 77.25% and 47.15%, respectively. Strain Y-10 had no function of dissolving phosphorus and potassium and producing IAA, but had the function of fixing nitrogen and producing iron carrier.