Stone brick pagodas of the Silla period developed separately from the conventional-style stone pagodas in a unique style. They can be classified into the brick-structure type and the imitation-brick structure type depending on their format. To date, stone brick pagodas were studied as a part of non-typical stone pagodas. In particular, the imitation brick structure stone pagoda has been found to have undergone diverse changes in style, which attracts attention. The imitation brick structure stone pagoda is classified into three types depending on the stylobate: those with post and lintel stylobates; stacked rock stylobates; and natural rock stylobates. Pagodas with post and lintel stylobates are further divided into those with a single-tiered stylobate and those with a two-tiered stylobate. Pagodas with stacked rock stylobates, which are only found in Gyeongju, are characterized by a stylobate formed from a pile of unrefined rocks, a main body without corner pillars, and a roof surface shaped like stairs. Pagodas with natural rock stylobates were built on a base of natural rock. Currently, the stone pagoda in Oya-ri, Gyeongju is the only remaining example of this type. The distribution of these pagodas is restricted to certain regions. They have been found only in the North Gyeongsang region, while pagodas with stacked rock or natural rock stylobates are specifically based in Gyeongju. Although it is without doubt that post and lintel stylobates appeared before the other two types, further study is required to determine the order of origin between stacked rock stylobates and natural rock stylobates. It is assumed that the style of pagoda with stacked rock stylobates was influenced by the way in which a natural rock was used as a stylobate, but no detailed attempt has been made to prove it. If the stacked rock stylobate is a recreation of the natural rock stylobate on flat ground, it is reasonably assumed that the earlier form consisted of stone pagodas with the main body and stair-shaped roof stone placed on a stylobate of natural rock. Therefore, it is thought that the stone pagoda with the natural rock stylobate in Oya-ri predates pagodas with stacked rock stylobates. Meanwhile, the areas where imitation brick structure stone pagodas were built were close to the transportation routes of ancient Silla, through which, it is understood, the style of imitation brick structure stone pagodas was imported into Gyeongju and affected the emergence of the stacked rock stylobates in the city. This indicates that the construction of imitation brick structure stone pagodas developed in the order of the pagoda with post and lintel stylobates, followed by pagodas with natural rock stylobates and pagodas with stacked rock stylobates. The last example of pagodas with stacked rock stylobates is the three-story stone pagoda in Jigok village in Yongjang Valley, which seems to have influenced the construction of pagodas with natural rock stylobates in Mt. Namsan, since the natural rock stylobate was more preferred on the higher part of Mt. Namsan. In addition, small-sized imitation brick structure stone pagodas continued to be built through to the Goryeo period, which indicates that the style of Silla pagodas was passed down to the Goryeo period. Lastly, in Gyeongju, where most of the pagodas were general type stone pagodas, the imitation brick structure stone pagoda featured a very unusual style. The emergence of the imitation brick structure stone pagoda shows the diversity and openness of the Buddhist art of Silla and carries art historical significance in terms of the emergence and development of the non-typical stone pagoda. Furthermore, as its style continued to the Goryeo period, it helps to understand a certain aspect of the development of the non-typical stone pagoda and the transmission of its style.