A cable assembly includes a connector, a cover enclosing the connector, a strain relief located on the rear end of the cover, a spring, and a cable. The cover includes a blocking. The strain relief is fixed by the blocking. The strain relief defines a through hole and a receiving cavity communicated with the through hole. The through hole has an inner diameter smaller than an inner diameter of the receiving cavity. A shoulder is formed between the through hole and the receiving cavity. The spring is received in the cavity, and has one end restricted by the shoulder and an opposite end restricted by the blocking. The cable is connected to the connector and runs through the spring and the through hole.