Abstract: Basalt fiber (BF) was modified by silane coupling agent and nano-SiO₂ particles-silane coupling agent, respectively. And the basalt fiber/epoxy (BF/EP) composites were prepared by winding process. The tensile properties of BF and the flexural properties of BF/EP composites were tested by universal material testing machine. The morphologies of BF surface and BF/EP composites flexural fracture were observed by FESEM. The long-term (2544 h) creep behaviors of BF/EP composites were tested by self-made three-point flexural creep test device. The short-term (6000 s) creep behaviors of BF/EP composites were tested by universal material testing machine at different stress levels. And the effect of fiber surface modification on the mechanical properties was analyzed. The results show that, with the introduction of nano-SiO₂ particles into BF sizing agent, the tensile properties of the fiber and the flexural properties of BF/EP are effectively improved. FESEM morphologies show that the synergistic modification of BF improves the bonding performance between the fiber and the resin. The creep compliance and its growth rate decrease significantly in the long-term creep tests with low stress for 2544 h and in the short-term creep tests with various stress levels for 6000 s. The stress threshold of linear creep of materials can be obtained from the coincidence curves of short-term creep tests at 20%, 30%, 40% and 50% stress levels. The Hooke-Kelvin-Kelvin (HKK) model can effectively describe the long-term creep performance of BF/EP composites at low stress level, so as to carry out the long-term prediction of its creep performance.