Housing is the second need after food for human beings. Since the housing crisis began with the increase in population, respective governments were forced to construct houses for a large number of families. Ignoring the qualitative aspects of these houses has caused social and cultural harm. Therefore, designers need to pay more attention to the quality of housing and living environments. The main objective of this study is to find the most important factors that affect the quality of low- income housing. In order to achieve this goal, the first stage of the research was to undertake a systematic review of the literature and interview the residents. The housing environment factors were classified in four categories: environmental, functional, formal and semantic factors. In order to give priority to the factors, a questionnaire was distributed among 15 experts (according to the Delphi technique, two rounds of surveys were taken). In the first round, some factors were removed and a new category was added. In the second round, experts gave priority to the factors. Once the data was collected, the next stage was to analyze it. The statistical analysis was performed using SPSS software (version 18 SPSS Inc., Chicago, IL, USA). The results obtained - based on the weighting of each factor - showed that some factors, such as interior space function, volume, relationship with nature, safety and social security are the most effective factors of low-income housing quality.