Abstract: In order to investigate the aging problem of glass fiber reinforced polymer(GFRP) composites as the lining of thermal power chimney, the glass fiber/epoxy(GF/EP) composite was taken as the research object. The effects of temperature, coupling agent content and heat flux aging time on the mass loss rate, bending strength and shear properties of GF/EP composite were studied by orthogonal test. The porosity of the GF/EP composite was measured and calculated by means of metallographic microscopic image processing and in-situ real-time detection system. The results show that different factors have different effects on the properties of GF/EP composites. The increase of coupling agent content can improve the mass loss rate of GF/EP composite. Temperature has a great influence on the bending strength. The post-curing behavior of the GF/EP composite itself will affect the change trend of bending performance, which still decreases by 11.8% as the temperature increasing. The interlaminar shear strength of the GF/EP composite is closely related to the thermal aging time, and the mean interlaminar shear strength is 10.2% higher at 16 h than that at 8 h.