About one out of every six prisoners is estimated to be infected with Hepatitis C Virus (HCV). Therefore, prisons offer a great opportunity to control the epidemic of HCV. New HCV treatments are very effective but are also outrageously expensive; thus prisons are pressed to prioritize treatment decisions for HCV-infected inmates. We propose a mathematical modeling framework and develop a spreadsheet-based decision support tool to support HCV treatment prioritization decisions in prisons. In particular, given the health and demographic characteristics, we compute a score for each inmate, and the inmates can be prioritized according to this score from highest to lowest. Our policy is easy to implement and we show through simulation that it has a significant performance improvement compared with the current practice.