The invention provides a method for improving tolerance of soybeans to petroleum and lead contaminated soil by applying photosynthetic bacteria, and relates to a method for improving soil tolerance. The method comprises the following steps of: before soybean seeds are sowed, spraying dilute bacterial agent to soil, diluting bacterial agent, soaking the seeds in the dilute bacterial agent and sowing the seeds; after the seeds are sowed, infiltrating dilute bacteria; and in the soybean growth process, monitoring the content of soybean chlorophyll every week from the seedling stage: selecting typical plants in a population, selecting fully-unfolded leaves at the topmost node positions, determining the content of the chlorophyll, or from the podding starting stage to the seed filling stage, respectively taking and spraying calcium chloride solution on leaf surfaces once, and then taking, diluting and spraying photosynthetic bacteria agent stock solution once. The method for improving the tolerance of the soybeans to the petroleum and lead contaminated soil by applying the photosynthetic bacteria has the advantages that the use cost is low, the process is safe, the environmental friendliness after use is good, the contents of the chlorophyll and carotenoid are increased very obviously, the plants are high, the stalks are thick, the dry weight and the fresh weight are greatly improved, the resistance indexes such as contents of proline, POD (peroxidase) and phytochelatin are improved, the content of malonaldehyde is reduced, the soybeans can tolerate the petroleum and lead contaminated soil, the physical and chemical properties of the soil can be remarkably improved and the soil fertility is improved.