We report the investigation of CN-PPV in poor solution. The fluorescence spectrum and the accompanying redshifted absorption spectrum suggest that the polymer forms interchain state in poor solution. As the concentration increases, the intrachain emission becomes weaker, while the interchain species emission becomes stronger. The fluorescence of CN-PPV film exhibits similar behavior to that in concentrated poor solution. A two-state model is proposed to describe fluorescence dynamics of polymers in films and solution.