Magnetic TiO2 (MT) composites were prepared and applied to degrading phenol, which is one of the listed priority pollutants. The effects of heat treatment under preparation on the photocatalytic activity of MT composites have been investigated by varying the soaking time under a constant final temperature of 823 K. The total organic carbon and ring-remaining intermediates of o-DHB, p-DHB and 1,4-BQ in solution were detected during the photodegradation of phenol. All the resulting MT composites were the single-phase anatase and magnetite judged by X-ray diffraction patterns. The calcination of the as-prepared particles was proven to be extremely crucial to the photocatalytic activity. The best condition of heat treatment was found to be soaking time of 2 h at T = 823 K due to the good performance of photocatalytic activity, stable magnetic property, and reusability over three times. The results lead to the conclusion that recyclable MT composites prepared in this study, which belonged to the category of recyclable green materials, exhibit good photocatalytic activity to degrade phenol so as to possess applicable potential for the degradation of refractory organics in the aqueous solution. Furthermore, the environmental and health impacts were reduced as MT composites were applied in the treatment of water pollution.