A detection device detects the integrity of a connection between respective connectors of two devices. The detection device includes a control chip, an electronic switch, and an alarm member. The control chip is connected to the alarm member through the electronic switch. When the detection device works, the control chip is connected to the detection pin of the first connector. When the first connector is properly connected to the second connector, the detection pin outputs a first signal to the control chip causing the electronic switch to be off. When the first connector is connected with the second connector improperly, the detection pin outputs a second signal and the control chip turns on the electronic switch, sounding an alarm.