"Mixed construction of platform" means the platform which was constructed by mixing heterogeneous materials such as roof tiles or bricks with divided stone of trimmed stone. This kind of construction technique was not known or found from the building sites of Goguryo or Silla so far and therefore it used to be understood as a unique platform construction technique or the product of technology and creativeness of Baikje's craftsman. The mixed construction of platform of Baikje came to position itself as one of the patterns of platform mainly used over Sabi period and we found the pattern from the sites including Imryugak site in Gongju, temple for royal tomb in Gwanbuk-ri, Wangheungsa Temple site, building site in Keumseong Mountain, Ohapsa Temple site in Byryeong. From the fact that they used a variety of materials which they could easily get around them such as roof tiles or bricks in addition to stones for the construction of platforms, we can see the feasibility and decoration characteristics of their material supply at that time. On the other hand, this mixed construction of platform was not popular in Goguryo and Silla, the major reason for which is judged to be non-existence of platforms to construct using bricks or roof tiles which could be constructed together with platform using divided stones. This is supported by the results of excavation of Hwangryongsa Temple site, Bunhwangsa Temple site, Heungryunsa Temple site of Silla which gave us comparatively abundant excavation data, and Jeongreungsa Temple site, Cheongamsa Temple site, Toseongrisa Temple site and building site in Daeseong Mountain castle and Anhak Palace site of Goguryo. For further progressive study on the mixed construction of platform of Baikje in the future, we will have to review more on the social background and technical background with the linkage with archeology and architecture at that time which led to the creation of such platform.