Background: SNF-related Kinase 1 (SnRK1) is a key component of the cell signaling network. SnRK1 is known to respond to a wide variety of stresses, but its exact role in salt stress response and tolerance is still largely unknown.Results: In this study, we reported that overexpression of the gene encoding the α subunit ofPrunus persica SnRK1(PpSnRK1α) in tomato could improve salt stress tolerance. The increase in salt stress tolerance inPpSnRK1α-overexpressing plants was found to correlate with increasedPpSnRK1αexpression level and SnRK1 kinase activity. AndPpSnRK1αoverexpression lines exhibited a lower level of leaf damage as well as increased proline content and reduced malondialdehyde (MDA) compared with wild-type (WT) lines under salt stress. Furthermore,PpSnRK1αenhanced reactive oxygen species (ROS) metabolism by increasing the expression level of antioxidase genes and antioxidant enzyme activities. We further sequenced the transcriptomes of the WT and threePpSnRK1αoverexpression lines using RNA-seq and identified about 1000PpSnRK1α-regulated genes, including many antioxidant enzymes, and these genes were clearly enriched in the MAPK signaling pathway (plant), plant-pathogen interactions and plant hormone signaling transduction and can respond to stimuli, metabolic processes, and biological regulation. Furthermore, we identified the transcriptional levels of several salt stress-responsive genes,SlPP2C37,SlPYL4,SlPYL8,SlNAC022,SlNAC042,andSlSnRK2family were altered significantly byPpSnRK1α, signifying thatSnRK1αmay be involved in the ABA signaling pathway to improve tomato salt tolerance. Overall, these findings provided new evidence for the underlying mechanism ofSnRK1αconferment in plant salt tolerance phenotypes.Conclusions: Our findings demonstrated that plant salt stress resistance can be affected by the regulation of theSnRK1α. Further molecular and genetic approaches will accelerate our knowledge ofPpSnRK1αfunctions, and inform the genetic improvement of salt tolerance in tomato through genetic engineering and other related strategies.