Sucrose non-fermenting-1-related protein kinase 2 (SnRK2) is a specific Ser/Thr protein kinase in plants. SnRK2 can regulate the expression of downstream genes or transcription factors through phosphorylation of substrates to achieve stress resistance regulation in different tissue parts, and make plants adapt to adverse environment. SnRK2 has a small number of members and a molecular weight of about 40 kDa, and contains a conserved N-terminal kinase domain and a divergent C-terminal regulatory domain, which plays an important role in the expression of enzyme. This review summarized the recent research progresses on the discovery, structure, and classification of SnRK2, and its function in response to various stresses and in regulating growth and development, followed by prospecting the future research direction of SnRK2. This review may provide a reference for genetic improvement of crop stress resistance.