The invention relates to an interface conversion device which is applicable to a storage device and comprises a first connection port, a second connection port, a measuring unit and a processing unit. The first connection port transmits first signals and power signals via a first communication interface. The second connection port transmit second signals and power sources to the storage device via a second communication interface, and the first communication interface is different from the second communication interface. The measuring unit receives the power signals from the first connection port, measures the power signals to generate measuring signals and outputs the power signals to the second connection port. The processing unit receives the first signals from the first connection port, converts the first signals into the second signals, outputs the second signals via the second connection port, receives the measuring signals and computes power consumption values.