The invention discloses a copper zinc tin sulfide thin film solar cell device based on a polyimide flexible substrate. 1. The polyimide flexible substrate thin film solar cell has a higher power to weight ratio, and has advantages of being flexible, foldable and resistant to impact. The solar cell device has great potentiality in cost reduction, and is suitable for rolling to rolling process in mass production. 2. Composition components of copper zinc tin sulfide are abundant in storage and are free from environmental pollution with low production cost. An energy gap of copper zinc tin sulfide is about 1.45eV which is very close to an ideal bandgap of 1.4eV of a photovoltaic cell. The copper zinc tin sulfide is a direct-bandgap p-type semiconductor material an optical absorption coefficient of which is greater than 10<4>cm<-1>, and thus is an ideal material for an absorbing layer of the thin film solar cell. The cell has high conversion efficiency, and theoretically reaches the highest conversion efficiency of a single-junction cell. The invention has the following advantages: the cell preparing method is simple, and easy to be implemented, and is conducive to massive popularization and application, and the method especially has a very important application prospect in aerospace and special occasions.