Experiments have been conducted to investigate the influence of the cusp external magnetic field (EMF) on deposition rate of two-electrode tungsten insert gas (T-TIG) welding. T-TIG arc parameters such as arc shape, arc voltage, arc pressure and arc plasma information were acquired respectively. Results showed compared to TIG, a higher welding current could be allowed for T-TIG, due to its low arc pressure characteristic. Under the effect of the cusp EMF, the arc shape was compressed along x-axis of T-TIG, while elongated along y-axis of T-TIG. Besides, the peak arc pressure of T-TIG was not significantly increased by the cusp EMF. Moreover, with the action of the cusp EMF, the maximum values of the electron temperature (Te) and electron density (Ne) of T-TIG were not significantly increased, but along y-axis, the increments of the two parameters were gradually increased and their distributions were widened. Therefore, more arc energy was allocated on y-axis of T-TIG by the cusp EMF, which could improve the preheating and the melting of the filler wire along y-axis, so the deposition rate of T-TIG could be increased by 17.6% under the effect of the cusp EMF.