Objective To translate the English version of the Medication Regimen Complexity Index into Chinese version and to cross-cultural debug its validation of the reliability, so as to provide a reliable tool of evaluating the degree of complexity of medication regimens for Chinese medical staff. Methods We translated and back-translated the Medication Regimen Complexity Index based on Brislin′s classical translation model. Pre-testing was performed after reviewed by a panel of experts to form the final version. Baseline information and medication regimens of 202 internal medicine discharges were collected for reliability testing. Results The inter-rater reliability of the Medication Regimen Complexity Index was 0.978, and the test-retest reliability was 0.988. A convergent validity test showed a significant positive correlation between the Medication Regimen Complexity Index score and the number of medications (r=0.938). Discriminant validity tests showed no correlation between Medication Regimen Complexity Index scores and age, BMI, education level, marital status, health insurance, and smoking status. The medication complexity rankings of the six cases, which were jointly performed by six experts, were in complete agreement with the rankings based on the Medication Regimen Complexity Index scores. Conclusion The Chinese version of the Medication Regimen Complexity Index has good reliability and validity and can be used by healthcare professionals to evaluate the degree of complexity of medication regimens for Chinese patients.