Abstarct: This study investigated the urban factors affecting the physical activity of citizens in the open spaces of Neyshabur city. The research method was descxriptive-survey.This research was a mixed exploratory study, which first identified the urban factors affecting physical activity through qualitative method through reviewing the literature of research and interviewing experts and then in quantitative prioritization and factor analysis. Statistical population in the qualitative sector included experts and experts in physical education, urban engineers and individuals who were active in open urban spaces. Purposeful sampling was used in this section with 15 theoretical saturation test subjects. Interviews identified 2 main variables of physical and social factors and 5 minor variables including access and location, safety and security, aesthetics, modeling and social networking. The statistical population was in an unspecified quantitative segment, including those who did physical activity in open spaces; the sampling method was available and, according to Klein (2010), sample size in factor analysis required 10 or 20 samples per variable, ten times the number. Our total is 340, but some questionnaires were filled out at the end due to the possibility that some of the questionnaires were confused. Data collection tool was a researcher-made questionnaire obtained from the qualitative phase of the study. The questionnaire consists of 5 components and 34 questions. Before applying the questionnaire, the face validity and content validity of the questionnaire were evaluated baxsed on expert rating and its reliability was confirmed by Cronbach's alpha (0.9). The results showed that the highest percentage of variables prioritization belonged to aesthetics with 25% and the lowest to social network with 15%. The results of factor analysis also showed that physical environment had a positive and significant effect on security and safety, aesthetics, access and location. On the other hand, social factors have a positive and significant effect on social networking. Finally, according to the results, urban factors have a significant impact on the physical activity of citizens in public open spaces. According to the findings of this study, more attention of experts on both physical and social variables is needed to increase the physical activity of citizens in the outdoor.