The method of inoculating environmental beneficial bacteria in pots was used for this experiment. Solid bacteria agents of six strains of environmental beneficial bacteria were applied to pots when the lettuce seeds sown and three weeks after sowing, respectively. The inoculation amount was 0.6%. The purpose was to study the effects of environmental probiotics on the growth of American Fast Lettuce（non-heading lettuce） and American Heading Lettuce. The results showed that the growth indexes of lettuce demonstrated that the growth-promoting effect of the six bacteria strains on two lettuce varieties were very obvious. However, the solid agents of different environmental beneficial strains had different effects on the growth of two lettuce varieties. The solid agents of strains Y₁, D-9, and Y₈ had the best effect on the growth of non-heading lettuce, and the solid agents of strains Y₈ and D-9 had the best effect on the growth of heading lettuce. In addition, the medium was used to prepare solid agent for environmental beneficial bacteria was composed of by-products of agricultural products and organic waste. After high temperature and autoclaving treat, it was used as a blank control in planting pots, which also had a certain promoting effect on the growth of lettuce. In short, the solid agents of the six strains have growth-promoting effects on lettuces. Among which the solid microbial agents of D-9 and Y₈ had very significant growth-promoting effects on two lettuce varieties, which is expected to be further application in the field production of lettuces.