Social capital is an important criterion in promoting the participation of villagers in rural projects. The aim of this paper is examining the role of social capital in participation of villagers in watershed plans in the Qareh Qeshlaq International Wetland in Bonab. This is an applied analytic descriptive research and it has been done using survey method. The study population of this research is the villagers, who are participating and the ones who are not participating in watershed plans. Using simple random sampling method, 200 people of heads of households were selected in Qareh Qeshlaq international watershed and 200 people were selected from village outside of the watershed as control group for the equality of test results. Validity of the questionnaire was confirmed by a panel of experts. Pilot study has been done in a region similar to the population study with 30 questionnaire and using the data obtained and Cronbach Alpha special formula in SPSS software, reliability of the questionnaire obtained 0.88 to 0.90.The study population of this research is 2446 people, consist of all of the heads of households in Qareh Qeshlaq international wetland and outside the watershed zone of this region. The results of Spearman correlation test and Regression in relation to the role of social capital in participation of villagers in watershed plans in two groups of villages showed that there is a significant relationship between social participation, social trust, social cohesion, satisfaction, tendency to joining to the institutions and knowledge with the dependent variable. And these variables is 85 per cent of rural participation in watershed management plans. Finally, according to the study findings, practical suggestions on practical and effective participation of villagers in various aspects of watershed management plans practical suggestions are provided.