The invention relates to a method for continuous production of an intermediate of a pyridine heterocycle insecticide, namely 2-chloro-5-methylpyridine. The method comprises the following steps: conveying 2-chloro-4-formylvaleronitrile, a chlorinating agent and an organic solvent into a kettle type mixing reactor through a metering pump for reaction, then putting into a three-stage kettle type reactor receiving kettle in an overflow form sequentially to perform continuous reaction, finally putting into a neutralizing kettle, and adding alkali to regulate the pH value of a system to be more than 7, thereby obtaining crude 2-chloro-5-methylpyridine. According to the method provided by the invention, the defects of high power consumption in intermittent reaction, non-uniform material mixing, difficulty in temperature control and effect of being prone to outshoot accidents are overcome, and the advantages of short reaction time, high selectivity in chemical synthesis reaction and high yield are realized. The method further has the advantages of mild conditions, stable quality, easiness in large-scale production, relatively low cost and relatively few three wastes, and is conductive to industrialized energy conservation, consumption reduction and production.