Receptor-like kinases (RLKs) play important roles in plant development and defense responses; however, their functions in other processes remain unclear. Here, we report that OsSIK2, an S-domain RLK from rice, is involved in abiotic stress and senescence process. OsSIK2 is a plasma membrane-localized protein with kinase activity in the present of Mn2+. OsSIK2 is expressed mainly in rice leaf and sheath, and can be induced by NaCl, drought, cold, dark and ABA treatment. Transgenic plants overexpressing OsSIK2 and mutant sik2 exhibit enhanced and reduced tolerance to salt and drought stress respectively compared to the controls. Interestingly, a truncated version of OsSIK2 without most of extracellular region confers higher salt tolerance than the full-length OsSIK2, likely through activation of different sets of downstream genes. Moreover, seedlings of OsSIK2-overexpressing transgenic plants exhibit early leaf development and delayed dark-induced senescence phenotype, while mutant sik2 shows opposite phenotype. The downstream PR-related genes specifically up-regulated by full-length OsSIK2 or the DREB-like genes solely enhanced by truncated OsSIK2 are all induced by salt and dark treatments. These results indicate that OsSIK2 may integrate stress signals into developmental program for better adaptive growth under unfavorable conditions. Manipulation of OsSIK2 should facilitate improvement of production in rice and other crops.