In experiments concerning electronics, communication and related engineering areas , researchers often need to measure and evaluate the power consumption of active devices. To meet this demand, this paper proposes a design of an efficient and automatic power measuring system based on MATLAB and builds the hardware and software platforms. The hardware consists of a computer and a programmable power supply, which communicate by a serial port. PC sends commands encapsulated by Modbus communication protocol to the programmable power supply, so as to realize control, monitoring and acquire the power supply’s output voltage and output current data that can be used to calculate the power of the active device. Experimental results demonstrate that this measurement system can measure the power of active devices, whose operation is quite convenient , stable, and efficient.