Objective Prosthetic loosening is the main cause of postoperative revision in unicondylar knee arthroplasty (UKA), and patient’s bone characteristics are important factors affecting the stability of the bone-prosthesis fixation interface. Methods In this study, a UKA finite element model was established to quantify the effects of five different bone quality conditions on the proximal tibial von Mises stress, bone-prosthesis fixation interface contact stress, and bone-prosthesis fixation interface micromotion, using the medial knee force and joint motion predicted by the individualized UKA musculoskeletal multibody dynamics model as boundary conditions. Results It was found that the influences of bone strength on the proximal tibia von Mises stress and bone-prosthesis fixation interface contact stress were not obvious, and the difference in the peak value of the proximal tibia von Mises stress between the two groups of models with the largest difference in bone strength was not more than 5%, and the difference in the peak value of the contact stress at the bone-prosthesis fixation interface was only 2.37 MPa; however, the influence of the bone strength on the micro-movement of the bone-prosthesis fixation interface was significant, and the weaker bones were more prone to cause the bone-prosthesis fixation interface micromotion. However, bone strength has a significant effect on the bone-prosthesis fixation interface micromotion, and weak bone is more likely to cause changes in the bone-prosthesis fixation interface micromotion, and the prosthesis fixation interface micromotion increased by 84.67% at 20% of gait cycles for patients with weakest bone quality compared to neutral bone quality. Conclusions UKA patients with weaker bone quality have a higher risk of prosthesis loosening, and it is recommended that surgeons should carefully choose their surgical strategy in order to reduce the rate of postoperative revision in UKA.