The accumulated evidence on marital quality indicates that marital communication training is necessary to reduce emotionally and economically cost of marital problems and decreasing divorce rates. However, despite the high effectiveness of Gottman’s intervention as one of the most effective family education training, Iranian researchers to date has tended to evaluate of Gottman approach in the individual counseling sessions, rather than empirically evaluation of the couple psychoeducational training. Empirically evaluation of Gottman’s psycho-educational intervention is not yet included in the previous studies among Iranian couples. The aim of this study was examined the effect of Gottman’s Psychoeducational Intervention (GPI) on marital communication pattern (MCP) among Iranian couple who have resided in Shiraz. This research was an experimental-longitudinal design with ۷۲ couples (n = ۱۴۴ individuals) from ۱۵۰ couples with consider of exclusion and inclusion criteria as well as screening by RDAS. The unit of analysis was the individual. The experimental group (۳۶ couples) underwent eight weeks of continual sessions of Gottman’s psychoeducational intervention and a one-year follow-up. Participants’ MCP was evaluated by communication patterns questionnaire (CPQ, Christensen & Sullaway, ۱۹۸۴). The findings of the research enhance our understanding of the longitudinal effect of GPI on MCP. The results of Repeated Measures ANOVA indicated that GPI can improve significantly participants’ constructive communication and decrease their total demand/withdraw communication and mutual avoidance communication across the time. This improvement was maintained after a one-year period among the participants in the experimental group. The effect of intervention was standard with no gender biases. The concepts of Gottman’s intervention include friendship, admiration, conflict management, and shared meaning system have significant efficacy to increase constructive communication and turn down mutual avoidance and demand-withdraw communication for couples. These results might be implied for family counselors and therapists to achieve a holistic and deep understanding of the underpinnings of marital life and, ultimately, help reduce the high rate of divorce in Iran and other countries.