Polyacrylonitrile (PAN) homopolymer was hydrolyzed by NaOH to a limited extent. Alkali hydrolysis was carried in a homogeneous solution state and heterogeneous aqueous dispersion state. The PAN homopolymer was dissolved into NaSCN and $ZnCl_2$ solutions, respectively. The carboxylic groups were introduced by hydrolysis of the nitrile groups within the PAN homopolymer main chain. The introduced carboxylic groups lowered the exothermic temperature and the heat of reaction. As the NaOH concentration increased, the exotherm maxima and heat of reaction decreased. Therefore, the fibers from the alkaline-hydrolyzed PAN possess potential for use in simple preparation of carbon fiber precursors.