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.