Colorless polyimides (CPIs) have been receiving attention as a flexible plastic substrate for applications in optoelectronics and various microelectronic industries because of their high transparency and low dielectric constants. CPIs are generally prepared in two steps by the synthesis of poly(amic acid) precursor and subsequent imidization of poly(amic acid). This conventional method uses organic solvents such as dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP). These organic solvents are damaging to the environment and lead to high production cost. To solve the problems, we developed a new green method to synthesize CPIs using distilled water as solvent. In this study, we compared different methods to prepare CPIs using organic solvent and distilled water. The CPIs synthesized by the green method showed higher molecular weight than the CPIs synthesized using organic solvent.