To improve the performance of thermoplastic composite joints and reduce the weight of joints, glass fiber (GF)/polypropylene (PP) thermoplastic composite rivets (GF/PP rivets) were prepared and tensile test and simulation analysis of GF/PP-riveted single-lap joints were carried out. Based on the tensile test, the optimum extension length of GF/PP rod with different diameters was determined by taking the specific joint strength (the ratio of joint strength to the weight of fasteners) as the evaluation index. The effects of the rivet diameter and the thickness of composite laminates on the specific joint strength and the weight reduction of GF/PP-riveted single-lap joints were studied. The joining mechanism and the failure behavior of GF/PP-riveted joints were analyzed by finite element simulation. The experimental results indicate that the specific joint strength of GF/PP-riveted joints decreased with increasing rivet diameter and laminate thickness. For the same specific joint strength, the weight of fasteners at joints could be reduced by 81.4% and 73.9%, respectively, by using GF/PP rivets instead of steel bolts and aluminum blind rivets. The simulation results show that the change of inclination angle of rivet body would cause the change of failure mode of joints.