Abstract: The molecular weight of a polymer plays an important role in studying its physical and chemical properties; thus, it is necessary to evaluate molecular weight before carrying out the following experiment process. Herein, three different polymers, poly(N-isopropyl acrylamide) (PNIPAM), poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(2-O-methacryloyloxyethyl-(2,3,4,6-tetra-O-acetyl-b-d-galactopyranoside)) (PAcGEMA), with the terminated Boron dipyrromethene (BODIPY) were synthesized. And gel permeation chromatography (GPC) and proton nuclear magnetic resonance (1H NMR) techniques were used to determine their molecular weight. Subsequently, end-group analysis method was used to determine molecular weight. The results showed that molecular weight measured by end-group analysis has similar values to that by GPC and NMR. Further, an amphiphilic copolymer of poly(AAPBA-b-GAMA) was synthesized, which was only dissolved in DMSO/H2O or DMF/H2O-mixed solvents and difficult to obtain molecular weight value by GPC or 1H NMR technology. Thus, its molecular weight was evaluated using end-group analysis method. These result implied that end-group analysis method has the potential to estimate molecular weight of polymers with the terminated BODIPY.