BACKGROUND: Despite significant progress in the reduction of under-five child deaths over the last decades in Ethiopia, still diarrhea remains the second cause of morbidity and mortality among under five children next to pneumonia. OBJECTIVE: To show trends and determinants of diarrhea among under five children in Ethiopia based on the four Ethiopian Demographic and health surveys data (2000-2016). METHODS: A total of 10,753 in 2000, 10,039 in 2005, 10,946 in 2011 and 10,337 in 2016 under five age children were involved in this study. Multivariate decomposition and multilevel analysis based on Bayesian approach was performed. RESULTS: Ninety seven percent of the change in diarrhea prevalence over time was attributable to difference in behavior. Being twin (AOR = 1.3; 95% CrI 1.1-1.5), big weight (AOR = 1.63; 95% CrI 1.62-2.02), not vaccinated for rotavirus (AOR = 1.44; 95% CrI 1.12-1.9) and for measles (AOR = 1.2; 95% CrI 1.1-1.33), poor wealth status (AOR 2.6; 95% CrI 1.7-4.06), having more than three under-five children (AOR 1.3; 95% CrI 1.1-1.61), member of health insurance (AOR 2.2; 95% CrI 1.3-3.8) and long distance from the health facility (AOR 2.7; 95% CrI 2.2-3.5) were more likely to experience diarrhea. CONCLUSION: The prevalence of diarrhea was significantly declined over the last sixteen years and the decline was due to difference in behavior between the surveys. Being twin, weight of child at birth, vaccinated for measles and rotavirus, number of under-five children, wealth status, distance to health facility, health insurance and child waste disposal method were significantly associated with diarrhea among under five children in Ethiopia. Therefore Ethiopian government should focus on the strengthening and scaling up of behavioral change packages of the community regarding to keeping hygiene and sanitation of the community and their environment, vaccinating their children, accessing health care services to prevent diarrheal disease.