Abstract: In order to further study the calibration technology of vector network analyzer and promote the low cost and universal application of electronic calibration units (ECU), the hardware system of electronic calibration units is built based on the general RF switch module and the open source Arduino control module. In order to let the ECU work under the nonideal situation, the solution algorithm of the system error term is deduced based on the fractional transformation characteristics. Finally, E5071C vector network analyzer and commercial E4431B electronic calibration units are used to build a comparison and test system. A filter for mobile communication system is used as the test object to verify the correctness of the ECU's hardware and the effectiveness of the error correction algorithm. The research results of this paper can provide reference for the low cost and general application purpose of ECU.