A system, a testing apparatus, and a method for testing at least one device with a connection interface are provided. The system comprises a host, a testing apparatus, and a power supply. The testing apparatus further comprises a microprocessor and at least one current limit module. The host sending a test signal. The power supply provides a voltage to the testing apparatus. The at least one current limit module of the testing apparatus, which is electrically connected to the microprocessor, the at least one device, and the power supply, provides the voltage to the at least one device. When the current passing through the at least one device is greater than the predetermined value, the at least one current limit module of the testing apparatus stops providing the voltage to the at least one device and sends an over current signal to the host via the microprocessor.