This paper presents both experimental and numerical studies on bolted glass fiber reinforced polymer (GFRP) joints subjected to uniaxial tension and different thermal conditions (−20 ℃, 20 ℃ and 60 ℃). Laboratory tests are conducted to obtain strength, elastic modulus and deformation of the joints. The numerical model is developed using the discrete element method (DEM) that can predict not only the above properties of the joints, but also the failure modes with detailed meso/micro damages that are in consistent with the observations from the tests. The DEM model is also used in the parametric studies to study the influence of the end distance to bolt/hole diameter ratio and the lap width to bolt/hole diameter ratio on the mechanical properties and failure models of the joints.