School Based Curriculum Development (SBCD) is emerged as a response to shortcomings and problems which stem from Centralized Curriculum Development and the most important reason for its formation is adopting curricula with existing needs and issues at school and community levels. In spite of increasing emphasis on dissemination of SBCD, the literature about curriculum has not properly addressed the status and role of needs assessment studies in SBCD and not only enough attention has not paid to this important issue, but also on independent study in this regard handly can be fined. The present article which is taken from a two years research in this area, tries to introduce a special model for curriculum needs assessment at school level and include various states of needs assessment. This model (SBCNA) is representative of a new research area in curriculum development. At the end of this article, after studying the existing situation in Iran, ways to pay more attention to needs assessment in school curricula has been considered.