Background <p>Health inequality remains a persistent challenge in rural areas, where limited healthcare accessibility is often associated with lower levels of health capital. In China, traditional Chinese medicine (TCM) service accessibility constitutes an important component of the rural healthcare system. However, whether and to what extent TCM service accessibility is associated with health capital and health inequality remains insufficiently understood. This study investigates whether, and through which mechanisms, TCM service accessibility is associated with health capital among rural residents and whether it is associated with lower health inequality.</p> Methods <p>This study uses micro-level survey data from 12860 rural residents across six provinces in China, combined with county-level healthcare resource statistics. The empirical strategy includes multivariate regression, instrumental variable estimation, mediation analysis, heterogeneity analysis, and inequality decomposition. Health capital is measured using a composite index constructed from four standardized dimensions: self-rated health, activities of daily living, chronic disease status, and objective physiological indicators (including blood pressure and fasting blood glucose). These indicators are aggregated using principal component analysis (PCA), with the first principal component used as the health capital index. TCM service accessibility is operationalized along three dimensions: supply availability, geographical accessibility, and individual utilization.</p> Results <p>The results show that greater TCM service accessibility is significantly associated with higher levels of health capital among rural residents. Specifically, a 0.1-unit increase in TCM service accessibility corresponds to an increase of approximately 0.021 units in the health capital index. The estimated effects exhibit significant heterogeneity, with larger magnitudes among individuals with poorer baseline health and lower income levels, and in settings with higher levels of social support. From an equity perspective, TCM service accessibility shows an equalizing association with the distribution of health capital, with a contribution share of −0.10 and an estimated contribution corresponding to approximately 0.030 of the health capital Gini coefficient. This represents the largest equalizing association among all examined factors, including income, education, and Western medical resources. Quantile regression results further indicate that the estimated effect at the 10th percentile of the health capital distribution is four times larger than that at the 90th percentile, suggesting larger estimated associations for disadvantaged groups. Mediation analysis suggests that healthcare utilization and health behavior are key potential pathways linking TCM service accessibility to health capital, with the total mediating effect accounting for 47.6% of the overall association.</p> Conclusions <p>The findings suggest that TCM service accessibility is associated with higher health capital and a more equitable distribution of health capital among rural residents. These findings highlight the equity-enhancing potential of traditional medicine within pluralistic healthcare systems and provide important policy implications for addressing persistent health disparities in resource-constrained rural settings.</p>