The joining of rubber polyester composite is affected by design and geometry parameters. These parameters affect the failure load of the composite joint and the failure mode. Catastrophic failure modes should be avoided, and the optimum parameters are selected to achieve a progressive failure that could be observed. Geometry parameters such as the edge distance and the center distance between holes are tested under tensile loading to get the optimum values. Design parameters such as tightening torque of bolt and washer size are also tested under tensile loading, and their effect on the failure load is obtained and studied. The failure modes are investigated under the digital microscope in each case. It is found that the failure load increases by increasing the edge distance, the tightening torque, and decreasing the center distance between holes. The optimum washer size is varied according to the used tightening torque. The optimum obtained failure mode in tests is a mixed - mode of bearing and net tension modes.