Trying for improvement performance as an essential principle, since of preliminary management creation, had been noticeable and more extensive every day. Today, it has prospect behaviors beyond the formal duties that are contextual performance, extra-role behaviors, Spontaneous behaviors or organizational citizenship behaviors. The other wise, the results of studies indicate that strain hinders of this behaviors. Therefore it's necessary schematization of plans and solutions for decreasing strain and then increasing OCBs. One of the most important of the activities is recognition of the effective variables on the OCBs for its preservation, increasing and reinforcement. This study with meta-analysis approach has recognized and studied the moderator variables that have been effective on this relationship. Statistical society is the hole of the studies that have investigating the relationship between strains and OCBs, total studies are 169 with 893 effect sizes, The results of studies revealed this relationship is moderated by five moderators of the characteristics of the study sample: the kind of job and organization (governmental vs. private), organizational position (managerial vs. nonmanagerial), the kind of employee (full time or no full time), and the number of statistic society.