One of the welding characteristics of aluminum alloy materials is that it is easy to produce gas pores. The existence of a large number of gas pores may not only reduce the strength of effective section of the weld,but also cause the damage of the welding structure and affect the service performance of the weld. There are many factors for the generation of gas pores in aluminum alloy welds. In this paper,through the welding tests of plates at different welding positions under the condition of fixed welding parameters, the relationship between the gas pore sensitivity of MIG welded joint of 5083 aluminum alloy and welding position is analyzed combining with the X-ray nondestructive testing results,and the distribution law of gas pore in the weld is summarized. The results show that under the same condition,the gas pore sensitivity is the highest when welding at horizontal position of welding. This is because at horizontal position of welding,arc is not straight to the molten pool,the pool is heated unevenly,and the stirring effect of arc on molten pool is weak.Appropriately optimizing welding para-meters and controlling environment can improve the sensitivity of welding gas pore and the welding quality reliability.