The invention belongs to the application field of bioengineering technologies, and specifically relates to a method for immobilizing nitrile-producing hydrolase namely gibberella intermedia CA3-1 (CGMCC No. 4903) by a chitosan-polyvinyl alcohol composite and a method for preparing nicotinic acid by using the immobilizing method. The method comprises the following specific steps of immobilizing the gibberella intermedia CA3-1, adding a proper amount of 3-cyano pyridine, and choosing a reaction condition which is the most suitable for immobilizing cells to obtain the nicotinic acid product. According to researches, the conversion activity of chitosan-polyvinyl-alcohol-immobilized cells is higher than that of small polyvinyl alcohol balls, and the reuse property of the chitosan-polyvinyl-alcohol-immobilized cells is also superior to that of the small chitosan-immobilized balls. The immobilized cells can be reused for a plurality of times, has high substrate tolerance and can be used for enhancing the production capability of unit cells. Therefore, the immobilized cells provide a precondition for preparing the nicotinic acid by using a biological conversion method, and lay a foundation for the industrial application of the gibberella intermedia CA3-1 (CGMCC No. 4903) in preparing the nicotinic acid from the 3-cyano pyridine.