Abstract: Preservice Primary School Teachers’ Understanding of Hierarchical of Quadruilateral. The research aims to described the preservice primary school teachers’ understanding of hierarchical classification of quadrilateral. The particapant of this research was 77 third year students in 2018/2019 of primary school teacher education program in Mulawarman University. To collect data, an open-ended question about classification of quadrilateral was addressed to participants and clinical interviews were conducted with them. The result show that the participants did not use the hierarchical definations of quadrilateral. The participants used the partitional definition. Therefore different relationships among figural concepts can be obtained based on the type of defination to be chosen. This study concluded that participants possessed to classification of quadrilateral, there were four type of preservice primary school teachers’ classification of quadrilateral.