Growing the urbanization and population tendency to urban environments has provided the situation for becoming important the urban life more than before. The overall objective of this study was to assess quality of life in informal settlements of Islamabad City in Zanjan province. The research method is descriptive – analytical and surveying. Method of gathering data is the field one and in a form of questionnaire , where 145 households were systematically selected as sample . In order to assess the life quality, both the objective and subjective aspects consisting 4 main indicators ( socio - cultural - religious , physical , economic and physical ) and 23 components have been used. Topsis and AHP model were used for the analysis of data in order to assess the quality of life in Islamabad .The research results indicate the difference in all indices but this difference is distinguished in economical and physical indicators. The results showed that firstly, Islamabad is placed at an undesirable condition from life quality indices and this difference is distinguished in economical and physical indices. firstly, there exists a significant and bilateral relationship between the indices in a district. thirdly, ,the subjective views of the citizens residing in Islamabad will change under the social cultural, economical and physical changes.