Urban Segregation is one the most important factors which has caused social and physical inequalities in cities. This phenomenon caused the high amounts of concentration of special groups in a certain place. The concentration of the poor or the rich can make them segregated from other parts of the city. Mashhad due to its high amount of migration is formed by different groups from different socioeconomic base. These groups due to their characteristics choose some especial places for living. Housing units can significantly help to identify the spatial pattern of city with regarding the fact that these places are a physical view of households' socioeconomic characteristics. Therefore this paper is going to study the occurrence of urban segregation phenomenon and its spatial patterns with the use of residential features and also identifying the most effective factor in occurrence of this phenomenon in Mashhad. For this purpose six residential variables like the size of family, the area of houses, the number of rooms in a house, the quality of houses and the ownership states of the house which are extracted from census of population and housing 1385, are studied in order to evaluate the segregation of various social groups in Mashhad. The research method is descriptive-analytical approach and for analyzing the data tow-group, multi-group, standard deviational ellipse and Arc Gis software are used. The results suggest that segregation has occurred between the eastern and western parts of Mashhad and the quality of Mashhad's houses in comparison with the other variables, has the higher multi-group segregation index and heterogeneous. Moreover, it is suggested that with increasing the area of houses and their rooms, the family size has decreased because disadvantage groups are not able to live in affluent parts of the city so since they want to have bigger areas with less price so they choose to live in eastern areas because these areas in comparison with western areas have smaller divided and cheaper lands. These things together cause this significant distinction between western and eastern parts of Mashhad that is a sign of segregation.