The long-term unreasonable application of chemical fertilizers in modern agriculture had directly led to the decline of soil and agricultural product quality. Microbial fertilizer substitution was an important way to solve these problems. Nine high-yielding strains of indole-3-acetic acid（IAA）were screened from the Bacillus library stored in the previous laboratory. The IAA secretion amounts of all strains are above 83.27 mg/L. Among them，T26 has the strongest secretion ability，which is 189.14 mg/L. Based on the comprehensive biological characteristics such as IAA production ability，iron carrier production ability，and antibacterial properties，four strains of bacteria（T26，PA8，DY15 and Ya6）were identified for further research. The results of molecular biological identification showed that T26，PA8，and DY15 belong to Bacillus subtilis， while Ya6 belongs to Bacillus velezensis. All four strains have the ability to produce iron carrier. Ya6 has a strong antagonistic ability against Fusarium. The research results of growth-promoting application ability showed that the seedling substrate added with high-yield IAA strains significantly promoted the seedling growth of tomatoes，peppers and glutinous corn. In tomato seedling experiment，T26，PA8 and DY15 had better growth promotion effects，and the plant height，stem diameter， fresh weight of aboveground and underground of tomato increased by 24.75%-51.34%，36.08%-43.67%，21.67%- 91.67%，11.63%-27.91%，respectively，compared with the control. The application of four strains of bacteria in lowfertility soil demonstrated superior growth-promoting effects compared to their use in seedling substrates. The plant height， stem diameter，number of leaves，leaf area，root length，above-ground fresh weight，and below-ground fresh weight of the treated pak choi plants showed significant differences compared to the control group. Specifically，these parameters were 1.80-2.08，1.38-1.70，1.50，2.80-3.69，1.12-1.72，4.18-5.85，and 4.45-6.41 times greater than those of the control， respectively. All four strains had good growth-promoting application potential，which would provide excellent strain resources for microbial fertilizer.