Overemphasis on the issue of ethnicity causes the more important reality of the nation and nationality to be forgotten and over time, the nation, ethnic group and ethnicity become a manifestation of loyalty and belonging. Therefore, it is necessary to emphasize the more important phenomenon of nationality and national solidarity while paying attention to the issue of ethnicity and the problems of ethnic groups, because nationality is a bigger umbrella that includes all ethnic groups. This research was conducted in order to identify the effective factors on promoting national solidarity and strengthening social capital in Sistan and Baluchistan province. In this research, the effect of five political, economic, social, ethnic-religious and cultural factors on promoting national solidarity and strengthening social capital has been studied and investigated. In terms of purpose, the current research method is practical and according to the type and nature of the problem, it is descriptive and analytical, which was used to collect information from a survey method using a questionnaire tool. The statistical population of this research includes all the residents of Sistan and Baluchistan province, who were calculated and selected as the sample size using the Cochran correlation. The value of Cronbach''s alpha for the questionnaire questions was calculated as 0.945, which indicates its high reliability. One-sample and two-sample t-tests have been used in order to check the proposed hypotheses. Finally, we have ranked the factors using the Friedman test. The results of the research indicate that all the five factors proposed and assumed affect the promotion of national solidarity and the strengthening of social capital in Sistan and Baluchistan province, and there is no significant difference in the opinions of the respondents in terms of their gender, ethnicity and religion.