In order to research the pores formation mechanism of sealing layer in laser welding of vacuum plate glazing, a laser sealing test was carried out. Scanning electron microscope, energy dispersive spectroscopy, X-ray diffractometer and metallographic microscope were used in this study. The influences of laser power and welding speed on pores of sealing layer were studied and the causes of pores were analyzed. The results show that, there are a large number of isolated pores in vacuum glazing sealing layer, which are different in size and disconnected with each other, located at the junction of particles, and mainly caused by the residual air between the solder particles. At the welding speed of 2mm/s and the defocus amount of -2mm, lower or higher laser power is not conducive to reduce the pore defects of sealing layer. When the laser power is 80W (energy density is 80J/mm2), the sealing layer has good morphology and good sealing quality. The lower welding speed will help to reduce the pore defects of sealing layer at the laser power of 80W and the defocus amount of -2mm. When the welding speed is 1mm/s (energy density is 160J/mm2), the sealing layer has good morphology and good sealing quality. This study can provide a theoretical basis for the laser sealing manufacturing of vacuum plate glazing.