Introduction: Despite of significant progress towards reproductive health, still in many societies menstruation is treating as negative, shameful or dirty consequences which may increases the incidence of reproductive tract infection leading to significant negative impact to a women’s health. To manage menstruation hygienically and with dignity, it is essential that women and girls have sufficient knowledge on menstruation hygiene management to manage it. Thus, this study aim to identify the knowledge and practice of menstruation hygiene and effectiveness of a health educational intervention on MHM. Methods: A school-based cross-sectional study was conducted between August 2021 to April 2022 among 400 secondary school girls studying in grades 9 and 10 in Chitwan District, Nepal. A total of 20 schools out of 250 schools were selected through lottery method. A further 400 girls were selected from selected schools by using systematic random method. Logistic regression analysis and Wilcoxon rank test were employed to identify predictors and evaluate effectiveness of health educational intervention on Menstrual Hygiene Management Results: Overall, 57.7% of the girls had unsatisfactory level of knowledge. Around two third (61.4%) missed schools days. Almost 99.5% had experienced any form of cultural restrictions. After health education intervention, level of knowledge about menstruation hygiene had significantly improved (z= 17.129, p=<0.001) in satisfactory level of knowledge compared to baseline (42.3% vs 92.5%). During multivariate analysis, studied in public schools (AoR= 1.7, p= 0.026), No or one close female friend (AoR= 2.2, p= 0.011), other than Brahmin/Chhetri caste (AoR= 1.4, p= 0.05), lived in joint family (AoR= 1.6, p= 0.048) were significantly associated with unsatisfactory level of knowledge on Menstruation hygiene management. Conclusion: Girls had unsatisfactory level of knowledge. School absenteeism and cultural restriction is very high. Ethnicity status, Types of family, Number of close female friends, types of schools and mothers’ education were associated with MHM. . Educational program conducted brings significant change in level of knowledge. Hence the education intervention demonstrate the suitability and feasibility of implementing a health educational intervention on MHM.