The main component of existing high-level radioactive sludge in China is phosphomolybdic heteropolyacid salt. Due to the low solubility of phosphorus and molybdenum in borosilicate glass, beyond certain solubility limit, phosphomolybdic heteropolyacid salt causes phase separation on the surface of glass and affects the efficiency and safety of vitrification. In this paper, the effect of PM content on the phase composition, microstructure and leaching resistance of borosilicate glass was mainly investigated. The results show that when PM content is 0%~4% (mass fraction, the same below), the sample is transparent glass. When PM content is higher than 5%, the sample is glass ceramic containing calcium molybdate and barium molybdate phases. With the increase of PM content from 0% to 6%, the ［SiO4］ structure in glass network structure gradually depolymerizes, the ［MoO4］2-structure gradually increases, the content of ［BO4］, Q3 and Q4 units in glass network decreases, and the compactness of glass network structure decreases. With the increase of PM content, the normalized leaching rates of Si, B and Na decrease first and then increase after 28 d, while the normalized leaching rate of Mo increases first and then decreases after 28 d.