Abstract: A unit cell model of creep mixing rate containing interface for glass fiber/resin composite (GFRP) was established to analyze the long-term creep property of GFRP. The experimental results of bending creep of GFRP under loads with the stress level of 20% of the initial bending strength were compared. The effects of interfacial modulus, interfacial thickness, fiber continuity, morphology and orientation on the long-term creep properties of composites were analyzed. The results show that this model is more accurate and more consistent with the experimental results compared with the mixing rate model without considering the interface effect. Interfacial modulus reflects the degree of binding between fiber and matrix, and affects the creep property of composite. The creep compliance decreases with the increase of interface modulus. The creep compliance of the composite increases slightly with the increase of the interfacial thickness. Compared with continuous fiber reinforced resin composites, the creep properties of chopped strand mat reinforced resin composite are more easily affected by interfacial effects. The fiber direction has a significant influence on the creep performance of composite materials. With the increase of fiber direction angle, the creep compliance of composite increases. However, when the fiber direction angle reaches 60°, the fiber has basically lost the load transfer and reinforcing ability, and the creep compliance of composite materials no longer increases with the increase of fiber direction angle.