Background: Post partum hemorrhage is one of the common causes in maternal morbidity and mortality and its outcome depends on accurate estimation of blood loss which needs acquiring skills. In this study, we decided to evaluate the effect of education on visual blood volume estimation by using simulation. Method: This prospective study was done in Mashhad University of Medical Sciences and 40 obstetrics and gynecology residents who had inclusion criteria and signed consent forms participated in it. The study was designed to include three stages; namely, pre-test, education-based simulation, and post-test. At first, six stations were simulated, along with, Post partum hemorrhage in different volumes (500, 1000, 1500, 2000, 2500 and 3000 cc). Then, participants were requested to fill their personal details in forms and view different simulated stations and estimate correct blood volume as pre-test. In the following stage, the researcher educated participants about correct volume in each station. In the final stage, six stations with the same volumes were simulated and the post-test was performed like the pretest. After data collection, it was statistically analyzed by SPSS software (version 11.5) and Chi-Square and McNemar Tests. P value less than 0.05 was considered significant. Results: Participants were 40 people of obstetrics and gynecology residents. The comparison between the results of pre- and post- tests, illustrated that the accuracy visual estimation in different blood volumes (500, 1000,1500,2000,2500, and 3000cc) had significantly differed (P= 0.008, P<0.001, P<0.001, P=0.001, P<0.021, P=0.001, respectively). Conclusion: Education via simulation had a significant effect on the accuracy of visual estimation of blood volume.