The invention relates to the field of analysis methods for detecting the weather resistance of titanium dioxide, and especially relates to a method for rapidly detecting the weather resistance of titanium dioxide. A technical problem to be solved in the invention is to provide the method for rapidly detecting the weather resistance of titanium dioxide by adopting the photochemical reaction of alcohol and titanium dioxide as a principle. The method comprises the following steps: 1, detecting a color difference delta E before and after illumination of a reference sample; 2, detecting the delta E of a sample to be detected by using processes in step a to step f in order to obtain the delta E of the sample; and 3, calculating the photocatalytic activity value of the sample. The photochemical reaction principle of the alcohol and the titanium dioxide is creatively used to realize the rapid and accurate detection of the weather resistance of the titanium dioxide. The method greatly shortens the detection time, effectively improves the detection accuracy and the timeliness of a detection result, and is suitable for various occasions needing rapid and accurate detection of the weather resistance of titanium dioxide.