The invention discloses a dust particle detection sensor and a dust detector with the same. The dust particle detection sensor comprises a laser device, a photoelectric receiver, a gas inlet pipe, a gas outlet pipe and a protective pipe. The laser device is used for emitting laser light sources, and a photo-sensitive detection region can be formed in irradiated regions of the laser light sources;the photoelectric receiver is used for receiving scattered light from the photo-sensitive detection region; the gas inlet pipe is used for delivering to-be-detected gas to the photo-sensitive detection region; the gas outlet pipe is used for delivering detected gas away from the photo-sensitive detection region; the protective pipe sleeves the outer side of the gas inlet pipe and is used for delivering clean protective gas, an isolation gas curtain can be formed on the outer side of the to-be-detected gas by the protective gas, and a pipe orifice of the gas inlet pipe extends out of a pipe orifice of the protective pipe. The dust particle detection sensor and the dust detector have the advantages that the protective pipe is arranged on the outer side of the gas inlet pipe, the protective gas can be sprayed out from the protective pipe, the isolation gas curtain can be formed on the outer side of the to-be-detected gas by the protective gas, the to-be-detected gas can be isolated in thephoto-sensitive detection region by the protective gas and can be prevented from contaminating external devices, and accordingly the service life of the dust particle detection sensor can be prolonged.