Abstract: A narrowband filter is used in passive vision, which allows light in a narrow wavelength range to transmit to format a clear image of weld pool. In the range of wavelengths,the radiation of weld pool is relatively high while the arc emittance is relatively low,so the disturbance of the arc is suppressed. In this paper,infrared transmitting filter is proposed for weld pool imaging based on the analysis of influencing factors,such as the spectral distribution of weld pool radiation,the spectral distribution of the arc emittance,and the spectrum response of the camera. Infrared transmitting filter makes maximum use of the advantage that at near-infrared band the weld pool radiation is high and the emittance of the arc is weak. At the same time,light in the larger wavelength range can transmit the filter,so image quality degradation due to the insensitivity of the camera is avoided. Experimental results of plused gas metal arc welding (PGMAW) process shown that clear weld pool images with details can be captured by the infrared transmitting filter during both the peak current period and the base current period of the P-GMAW process.