In this paper we present the physical layer (PHY) MODEM certification system of the power line communication Korea standard (PLC-KS). The PLC-KS is basically very similar to the U.S. PLC standard, Home-Plug1.0, except that bit loading is used in the PLC-KS. However, similar to Home-Plug1.0, the discrete multi-tone (DMT) with differential phase shift keying and the frequency diversity are also adopted to improve the link reliability. Based on this PLC-KS, we develop the PHY MODEM certification system where we check if the MODEM provided by the chip manufactures conforms to the standard. For this purpose we propose the following three different certifications: 1) preamble certification, 2) control and data frame certification, and 3) wave-shaping certification, which are strictly enough to confirm if the manufactured MODEM conforms to the PLC- KS. Although our certification system is based on the PLC-KS, its methodology can be extended to the communication chips manufactured based on other communication standards.