Abstract: Somali Jet changes will lead to the variability of Asia monsoon and climate. What would be the changes of Somali Jet and its response to the global warming in the future climate? To focus on the questions, we first valuate the ability of IPCC AR4 climate models for the 20th century experiment (20C3M) to reproduce the observed features of the low level Somali Jet in JJA (June-July-August) in terms of climatology for the period 1976-1999. Then, we discuss its changes under the climate changes of scenarios A2 for the period 2010-2099. The results show that 18 IPCC AR4 models have reasonable capabilities to describe the climatologically features of Somali Jet in the present climate simulation. The analysis of intensity of Somali Jet changes from the multi-model ensemble results for the period 2010-2099 are mainly characterized by: the weakened Somali Jet in the early 21st century (2010-2040), the enhanced (strongest) Somali Jet in the middle 21st century (2050-2060) as well as the weakest Somali Jet in the end of 21st century (2070-2090). Compared with the period 1976-1999, the intensity of Somali Jet in the 21st century is weakening in general and become weakest at the end of the 21st century. The results also suggest that relationship between the increment of intensity of Somali Jet in JJA and the increment of global mean surface air temperature is nonlinear, which is described differently among the models, suggesting the uncertainty of the IPCC AR4 models. Considering the important role of Somali Jet in the Indian monsoon and East Asian monsoon and climate in China, especially, the variability of Somali Jet and its evolvement under the present climate or in the future climate changes should be further emphasized.