Photochemical degradation of dimethyl phthalate (DMP) in Fe(III)/tartrate/$H_2O_2$ system was investigated utilizing fluorescent lamps as the primary light source. Effects of initial pH, light source, and initial concentration of each reactant on DMP photodegradation was examined. The results show that the system was able to effectively photodegrade DMP utilizing visible light. Fluorescent lamp, halide lamp, UV lamp and sunlight could all be used as the light sources. The optimal pH ranged among 3.0-4.0 for the system. Increases of the initial concentrations of Fe(III) and $H_2O_2$ accelerated the photodegradation of DMP, whereas excessively high initial tartrate concentration resulted in the decrease of photodegradation efficiency and rate of DMP.