Abstract: Provided is a composite powder used for the visible light catalytic and anti-bacterial purposes. The composite powder includes a plurality of N-type semiconductor particles and a plurality of P-type semiconductor nano-particles. The P-type semiconductor nano-particles cover surfaces of the N-type semiconductor particles respectively. A weight ratio of the N-type semiconductor particles and the P-type semiconductor nano-particles is in a range of 1:0.1 to 1:0.5. A PN junction is provided between each of the N-type semiconductor particles and the corresponding P-type semiconductor nano-particles.