Titanium dioxide was developed in 19th century and widely used as an artist’s pigment since 20th century. Due to the photocatalsis of titanium dioxide, it can decompose the organics so that the organic dye and binders of painting could be destroyed, resulted in fading, chalking and loss of gloss. In order to figure out the potential dangers of titanium dioxide to the painting, a quick testing method by liquid state UV-VIS spectrometer is used to measure the photocatalytic activity of titania. However, it is proved not suitable for the testing of whole artist’s pigment since many limitations of experimental process make the testing results inaccurate. In this case, solid state spectrometer is applied instead of liquid state spectrometer. A new photocatalytic activity test is developed, including the new sample preparation and measuring method. Based on the new developed testing method by solid state spectrometer, the influence of titanium dioxide on the degradation of selected artis’s pigment or dye can be measured. And the problem of limitations of original testing method is solved well.