BACKGROUND: Children are one of the most vulnerable social groups to infectious diseases, and prevention of urinary tract infections in children is very important; therefore, the present study aimed to investigate the effect of education based on health belief model (HBM) on promoting preventive behaviours of urinary tract infection in mothers with children under 6-years of age. METHODS: This quasi-experimental study was conducted on 150 women with children under 6 years of age referred to health centers in Fasa city, Iran in 2021. Subjects were selected using simple sampling method and were randomly divided into intervention (n = 75) and control (n = 75) groups. The educational intervention for the experimental group consisted of 6 virtual training sessions of 40-50 min using lecture, question and answer, group discussion and video clips. Two virtual follow-up sessions were also held one month and two months after the educational intervention. Three months after the educational intervention, both experimental and control groups completed the questionnaire. Data were analysed by using SPSS 22 through Chi-square, independent t-test, and paired t-test (p > 0.05). RESULTS: Before the intervention, based on independent t-test and paired t-test, the mean score of HBM constructs were not significantly different between the control and intervention groups (P > 0.05). However, while perceived barriers significantly decreased (P < 0.05) after the intervention, the mean score of knowledge, ‌ perceived sensitivity and severity, perceived benefits, ‌ self-efficacy, cues to action, and performance significantly increased (P < 0.05) after the intervention. CONCLUSION: Considering the effect of training preventive behaviours of urinary tract infection based on HBM, application of the model as an effective and cost-effective method along with other methods is recommended for educational programs of mothers with children under 6 years of age.