A server system includes a number of servers and a server holder. Each server includes two opposite sidewalls with each having a sliding rail formed thereon. The server holder includes two opposite lateral plates and a number of supporting structures. Each lateral plate defines a plurality of rows of receiving holes. Each supporting structure is received in one receiving hole, and includes a supporting block and a torsion spring positioned on the supporting bock. The supporting block is pivotably connected to one of the lateral plates, defines a sliding slot, and includes a resisting surface facing towards interior of the server holder. The sliding rail is slidable along the sliding slot. The torsion spring is configured for providing an elastic force to push the supporting block to keep the resisting surface resisting against one sidewall.