Abstract: In response to the problem of poor side wall fusion of narrow gap tungsten inert gas(TIG) , this article adopts the method of tungsten electrode center ventilation to expand the welding arc and transfer the arc heat to the groove side wall to ensure sufficient fusion of the narrow gap groove side wall. On the basis of building a hollow tungsten electrode center ventilation narrow gap welding system, the influence of parameters such as center gas flow rate on the weld forming size and arc shape is studied. The results show that compared with solid tungsten electrodes and hollow tungsten electrodes, the narrow gap welds melting width and side wall melting depth obtained by the hollow tungsten electrode center ventilation method are increased. Under the same parameters, the solid tungsten electrode welds melting width is 9.32 mm, the hollow tungsten electrode without ventilation obtains a melting width of 9.91 mm, and the melting width increases to 11.02 mm after the center ventilation; As the gas flow rate at the center of the hollow tungsten electrode increases, the width of the narrow gap weld and the depth of the side wall melt also increase. When the gas flow rate reaches the critical value (≥ 0.8 L/min), a side wall incomplete fusion defect occurs. The introduction of inert gas into the center causes the electron channel to transfer to the peripheral area of the hollow tungsten electrode, thereby improving the problem of poor side wall fusion of narrow gap TIG.