Abstract: The working temperature of the existing high-temperature basalt fibre filter bag is 280℃, they are difficult to work for a long time when the temperature is above 300℃. In order to improve the heat resistance of basalt fibres, in this paper, a kind of water-soluble zirconium hybrid silicone resin sizing agent was synthesized and used for basalt fibre surface modification. Microstructure and properties of zirconium hybrid silicone resin and modified fibers were characterized by FTIR, TG-DSC, SEM, AFM, DCA and tensile test. The results show the decompose temperature of zirconium hybrid silicone resin is 323-360℃. The surfaces of the sized fibres are coated by dense and uniform silicone resin films. These films increase the surface roughness and surface areas of the fibre surfaces, improve the surface energies, change the surface morphologies, repair the surface micro defects. Themechanical tests show that after heat treatment of 2 h at 300℃, the breaking force of optimum sample is 376.0 N, and the breaking elongation is 2.647%, which are better than the related performance of uncoated fibre (287.8 N, 1.932%). Therefore, the zirconium hybrid silicone sizing agent could significantly improve the heat resistance of basalt fibre.