In view of the current PLC communication test equipment, it has low accuracy and poor reliability in the aspect of anti-interference performance test . The technical of test system and key technical of anti-jamming test are analyzed. The paper focuses on electromagnetic conduction and radiation crosstalk and multipath interference in the frame of test system , The inaccuracy and instability of LC attenuator and matrix are briefly described , put forward the improvement plan. Based on the key components such as high performance EMI filter, shielding box and coaxial programmable attenuator , the existing test system is improved. After the receiving sensitivity and the demodulation threshold SNR test , the test process is more stable, and the test results is more reliable and more precise , improved scheme is suitable for point-to-point communication performance test, and also can be applied to the test of the PLC communication network route capacity.