In this work, the photoconversion of 1-chloronaphthalene (CN-1) and 2,3-dichlornaphthalene (CN-10) under the simulated sunlight had been studied. The results showed that the photoconversion of CN-1 and CN-10 obeyed the first-order kinetics model. NO2 -, NO3 -, Fe3+ and Fe2+ extensively present in natural water can accelerate CN-1 photoconversion via generating ·OH, which may induce indirect photooxidation of CN-1. The photoproducts were treated by the derivatization method and analyzed by GC-MS after being irradiated for 6 h. Ten products were characterized for CN-1 and CN-10, and there were six common products. On this basis, the photoconversion pathways of CN-10 and CN-1 were proposed, and both of them have a similar conversion mechanism.