The invention relates to a salt-tolerant growth-promoting bacterium strain D5-2. The salt-tolerant growth-promoting bacterium strain D5-2 is preserved in the China General Microbiological Culture Collection Center on the preservation date of 5 May 2019 with the preservation number being CGMCC NO.17706, and the 16S rDNA nucleotide sequence of the salt-tolerant growth-promoting bacterium strain D5-2is as shown in SEQID NO.1. When the strain D5-2 is inoculated, under salt stress, the salt-tolerant growth promoting capacity of solanum lycopersicum can be notably improved. The strain is prepared into a microbial inoculum, and then the microbial inoculum is injected into rhizosphere soil of solanum lycopersicum seedlings, so that the plant type, the plant height and the stem thickness of the solanum lycopersicum can be obviously enlarged, the dry matter accumulation of the solanum lycopersicum seedlings can be notably promoted, the microbial inoculum has promoting effects on the root length, the surface area, the root volume and the number of root tips of the solanum lycopersicum seedlings, a salt injury phenomenon is alleviated, the growth of the solanum lycopersicum seedlings is promoted, and increase of salt tolerance of the solanum lycopersicum is facilitated.