Solar light pipe combined with photocatalysis could introduce sunlight into rooms and also has air purification function. The length of the solar light pipe is 0.55 m with a diameter of 0.28 m. The average ratio of reflection of the surface of solar light pipe is 0.82. Snow shaped astigmatism board has a diameter of 0.28 m. Coating DegussaP25 solution evenly on the rugged side for the quality of 1.75 g. The experiments show that when the coating side away from the sun the lighting degree may be reduced compared with when facing the sun. But the average reduction was only 3.03 percent which would not have a significant impact on indoor lighting. The experiments also show that in a sunny summer morning under the direct sun, Solar light pipe combined with photocatalysis could reduce formaldehyde in a little box of 0.1 m3 volume from 1.0×10-6 to 0.19×10-6. Under the direct noon sun within 1h formaldehyde volume from 1.0×10-6 down to 0.17×10-6 with faster and more complete degradation of formaldehyde. In direct afternoon sun within 1 hour, the volume fraction of formaldehyde reduced from 1.0×10-6 down to 0.2×10-6. The rate of degradation in the afternoon was slower than that in the morning and noon, but also achieved a good performance.