The invention discloses an application of a tomato transcription factor gene SlNAC2. The invention relates to application of a tomato transcription factor gene SlNAC2 in improvement of salt tolerance of tomatoes and/or reduction of atrazine residues of tomatoes. The nucleotide sequence of the tomato NAC transcription factor gene SlNAC2 is as shown in SEQ ID NO.1. The invention also discloses application of the tomato NAC transcription factor gene SlNAC2 in improvement of salt tolerance of tomatoes and/or reduction of atrazine residues of tomatoes. According to the invention, an NAC2 transcription factor SlNAC2 is cloned from tomato, and a transgenosis experiment further proves that the SlNAC2 has a positive regulation function in a process of responding to salt stress; the overexpression of the SlNAC2 significantly reduces the residue of atrazine, and improves the metabolic degradation ability of tomato plants to the residue of atrazine. The SlNAC2 gene identified by the invention is beneficial to analysis and research of a mechanism of tomato responding to salt stress and degrading pesticides by metabolism, and can be used for cultivation of salt-tolerant tomato and low-pesticide-residue tomato varieties.