New Seoul Town is a new town in Seoul Mapo-Gu, Which is planed by Seoul metropolitan government. There are Nanji Waste reclaimed land and Seoul world-cup stadium, which is under construction in the new town. This study is executed for urban nature conservation by assessing the biotope in the new town. The biotope map is mae by the selective mapping method, and assessing the biotope is executed by a quick method, which is originated with R. Wittig and Scheriber(1983). The assessment criteria include the period of development, area, rarity and variety of habitat condition. In the result from this study, biotope type of the new town is classified eight types, and all biotope type is valuable for nature conservation. The reason of this result is because of little natural area which is rice field, farm field, forest, swampy land, etc, except New Seoul Town, in Seoul Mapo-Gu. And so, Biotope in New A Seoul Town, must be conserved and restored in new town urban planning.