A fastening system includes a first connecting member, a second connecting member, a rivet, and an elastic member. The second connecting member is positioned on the first connecting member, and defines a receiving groove. The rivet extends through the first connecting member and the second connecting member, and rivets the first connecting member and the second connecting member together. The rivet forms a riveting flange at an end adjacent to the second connecting member. The elastic member is received in the receiving groove of the second connecting member, and compressed by the riveting flange to generate a predetermined positive pressing force between the first connecting member and the second connecting member. A fastening device for manufacturing the fastening system is also provided.