The mothers of children undergoing colostomy usually do not receive sufficient information about colostomy care and prognosis; hence, they experience many problems. Simulation-based education not only increases mothers' knowledge but also improves their skills.   Aim: to evaluate the effect of simulation-based education about colostomy on mothers' knowledge, and practice among their children. Design: quasi-experimental one group pretest-posttest research design was utilized to achieve the aim of the current study. Setting: The study was conducted at pediatric general surgical unit which located at the fourth floor in Cairo university specialized pediatric hospital (CUSPH). Sample: A convenient sample of 60 mothers of children with colostomy was participated in the study. Data collection tools: structured interview sheet and questionnaire of mothers' knowledge and checklist to evaluate mothers ‘practices about colostomy. Results:  After using simulation based education mothers had higher score of knowledge and there were highly statistically significant difference (p< 0.001). was detected between total mean score of mothers' knowledge in the pretest, immediate posttest and before discharge. Also there was higher score of practice, more competent and statistically significant improvement (p < 0.001) were detected mothers' practice regarding colostomy care in immediate, second, third and before discharge. Conclusion: Simulation based education is appropriate method in health education for mothers as it has a positive effect on improve the mothers' knowledge and practice regarding care of children with colostomy. Recommendation: Integration of the simulation based education for mothers of children with colostomy and incorporated into the discharge plan to get the best outcomes for mothers and their children.