In this work, a mixture of acetone and dimethyl sulfoxide (volume ratio 1∶1) and a particular covering method using degreasing cotton and preservative film was applied to remove the oil paint from the surface of a Zhen’an Temple iron bull. The solvent mixture and the covering method quickly and efficiently removed the oil paint film. The optimum mixed reagent for dissolving the oil paint film was selected by referring dissolution experiment photographs and Fourier transform infrared spectra. Besides, scanning electron microscopy and energy dispersive spectrometry were employed to test the dissolution behavior of the mixed reagent. The mixed reagent could dissolve the oil paint film without harming the iron bull matrix. The concept of "three dimensional solubility parameters" was applied to explain the dissolution action of the mixed reagent. Additionally, the theoretically optimum solvent volume ratio of the mixed reagent could also be inferred using the concept. The covering method and a hair drier were adopted to purge the damp and warped oil paint film after the immersion in the mixed reagent. This thermal drying method could quickly blow off the paint film from the surface layer of the Zhen’an Temple iron bull with a good effect.