Abstract: order to surmount the technological difficulties caused by the narrow gap effect, a transverse magnetic field is applicable to deflect the arc, so that a consistent fusion of the side wall can be achieved. Description is given of investigation about the effect of transverse magnetic field on electric field distribution in the arc column, the effect of magnetic field and welding parameter on the current distribution to the backing plate and the side walls, introduction of a rational coordinative method of the relation between pulsed welding current and transverse magnetic field. The results of the study may lead to improve the practical of use TIG in narrow gap welding.