Four years. According to official website of Zhengzhou University, the doctoral program of pharmacy lasts for 4-8 years, and some outstanding students can finish their doctoral studies and graduate smoothly within four years at the earliest, that is, the four-year program. Zhengzhou University, referred to as "Zheng Da" for short, is located in Zhengzhou and is a university jointly established by the Ministry of Education and the Henan Provincial People's Government.