Abstract: To investigate the influence of water absorption rate on electrical properties of low smoke zero halogen flame retardant polyolefin cable material, water absorption rate was regulated by adjusting the ratio of ethylene-vinyl acetate copolymer (EVA) to metallocene linear low-density polyethylene (mLLDPE). Dielectric constant, dielectric loss tangent, immersion capacitance, volume resistivity, and immersion breakdown strength under different water absorption rates were systematically measured, and the effect of irradiation cross-linking on breakdown performance was examined. Results showed that with the increase of water absorption rate, dielectric constant, dielectric loss tangent and immersion capacitance increased gradually first and then sharply, while immersion breakdown strength decreased sharply initially and then more slowly. In a high-humidity environment, possible residual microcracks or free radical sites from irradiation cross-linking combined with polar groups, enhanced interface polarization and ionic conduction, led to a sharp rise in leakage current and a continuous decrease in breakdown strength, eventually approaching the level of non-crosslinked materials. Under conditions of low water absorption rate, three-dimensional network structure formed by irradiation cross-linking restricted molecular chain movement, reduced internal voids, resulting in a higher and more slowly varying breakdown strength. The study could provide a reference for predicting electrical properties of cable materials based on water absorption rate and improving their long-term reliability.