Objective: The present study was conducted to investigate the effect of transdiagnostic treatments on worry and rumination of mothers of children with autism spectrum disorder (ASD). Methods:The study population included all mothers of children with ASD in Isfahan City. Among mothers of children with ASD, 40 individuals were selected from those who obtained the highest scores in worry and rumination (At least one SD higher than the mean scores of the group) and were randomly divided into control and experimental groups. To collect data, the Rumination Response Scale (RRS) and Penn State Worry Questionnaire (PSWQ) were used. The data were analyzed through multivariate analysis of covariance (MANCOVA) using SPSS-21. Results:The results indicated that the transdiagnostic treatment is effective on the rumination (F=26.91, df=1 and 36, P<0.001) and worry (F=10.86, df=1 and 36, P<0.002). Conclusion:Transdiagnostic treatment method can be an effective educational program for reducing emotional problems in mothers of children with ASD.