The existing literature has demonstrated that variables such as gender, body mass index (BMI), and age play a significant role in the risk assessment of hiatal hernia. This study aims to comprehensively investigate the association between these risk factors and hiatal hernia through a retrospective analysis and Mendelian randomization (MR) analysis.In this study, the examination results and basic information of 685 patients who underwent routine esophagogastroduodenoscopy (EGD) at the gastroesophageal Reflux Center of Xuanwu Hospital from 2018 to 2024 were retrospectively collected. logistic regression was used to analyze the potential risk factors. Meanwhile, a two-sample MR analysis was used to further validate and supplement these risk factors.A retrospective study showed that the incidence of hiatal hernia diagnosed by endoscopy was 28.7%, in the population without GERD, the incidence was 22.8%In the multivariate logistic regression analysis, male sex (P = 0.033), age (P < 0.001), heavy physical labor (P < 0.001), and gastroesophageal reflux disease (GERD) (P < 0.001) were independent risk factors for hiatal hernia, while an increase in BMI, smoking, alcohol consumption, and the number of pregnancies and deliveries in women were not statistically significant. The inverse variance weighting (IVW) results of the MR analysis showed that an increased waist-hip ratio (ORIVW = 2.57, CI 1.32-5.01, P = 0.0057), trunk fat (ORIVW = 3.53, CI 1.76-7.07, P = 0.0004), smoke initiation (ORIVW = 1.47, CI 1.02-2.13, P = 0.0408), and alcohol intake frequency (ORIVW = 2.23, CI 1.18-4.20, P = 0.0134) were associated with hiatal hernia, but the causal relationship between alcohol intake frequency and hiatal hernia was not established.This study showed that male gender, age, heavy physical labor, and GERD were independent risk factors for hiatal hernia. MR analysis showed that abdominal obesity and smoking may be genetically associated with hiatal hernia. However, there was no statistical significance between increased BMI and hiatal hernia in multivariate analysis and MR analysis.© 2025. The Author(s).