The invention provides a device and a method for detecting the mass concentration of a particulate matter, and relates to the technical field of concentration detection. The device for detecting the mass concentration of the particulate matter comprises a gas channel to be measured, a gas flow driver, and a light scattering measurement unit, a flow metering unit and a matched control processor which are arranged on the gas channel to be measured, and also comprises a micro-resonance measurement unit arranged on the same gas channel to be measured together with the light scattering measurementunit, the micro-resonance measurement unit includes a choked flow filter membrane arranged on the gas channel to be measured, and a frequency detector and a control circuit which are connected with the choked flow filter membrane, and the signal output end of the frequency detector is connected with the control processor. The device and the method, which adopt a micro-resonance process and a lightscattering measurement process to carry out fusion calculation, have the advantages of high mass resolution, fast response speed, suitableness for various gas channels, overcoming of the influences of the physical, chemical and flow characteristics of particles on the simple light scattering measurement process, and accuracy and reliability in the measurement result.