The present study was conducted with the aim of investigating the relationship between parents' marital satisfaction and preschool children's sleep problems, mediated by separation anxiety disorder. A total of 400 preschool children (228 boys and 172 girls)aged between 3 and 6 years in Tabriz city were selected by multi-stage cluster random sampling method in 2014-2015.Their mothers answered a questionnaire measuring children's sleep habits, parent-child separation anxiety scale, and Enrich marital satisfaction scale. The data were statistically analyzed using structural equation modeling and SMARTPLS-3 software. The results showed that in addition to the direct relationship between parents' marital satisfaction and preschool children's sleep problems, marital satisfaction is mediated by separation anxiety disorder Children's sleep has significant indirect effects (at the 0.01 level), so the results indicate the mediating role of separation anxiety disorder in the relationship between parents' marital satisfaction and children's sleep problems. Therefore, it can be concluded that the quality of marital relationships can be a good starting point for the prevention and early treatment of children's sleep problems, and the increase in parents' marital satisfaction will lead to children's sleep health, and these findings may be useful for mental health professionals, including therapists, psychologists and counselors to occur.