A total of 78 strains of bacteria were isolated from potato rhizosphere soil and leaves by three different cultures. The dominant genus was Pantoea，accounting for 55.13% of the total number ofstrains.The diversity of bacteria isolatedfrom potato rhizosphere soil using R2A medium(27 dominantbacterias，13genera)was relativelygood，followed by Ashbymedium(31 dominantbacterias，9genera)，and soil extractmedium(1 dominantbacteria，1genera)was theleast.The bacterial diversity of endophytic bacteria isolated from potato leaves by Ashbymedium(19 dominantstrains，3genera)waspoor.The ability of IAA production was quantitatively determined by Salkowski colorimetric method.The resultsshowed that 58 strains had the ability to secrete IAA，accounting for 74.36% of the total strains tested.The number and diversity of IAA-producing bacteria screened from potato rhizosphere soil(42 dominantbacteria，13genera)were higherthan those from potatoleaves(16 dominantbacteria，2genera).Seven IAA -producing strains were selected to study their growth-promoting characteristics and potato seedling growth-promoting ability according to the difference of IAA-producingability，isolation site and isolationmedium.The results showed that six IAA -producing bacteria had the ability of ACCdeaminase，one IAA -producing bacteria had the ability of dissolving inorganicphosphorus，and two IAA -producing bacteriahad the ability of dissolving organicphosphorus.Twice greenhouse growth -promoting experiments showed that strain Pantoea sp.MLS-34-25 had obvious growth-promoting effect on potato seedlings and was a potential strain for microbial fertilizer production.