The present invention provides a plural third harmonic generation (THG) microscopic system and method. The system includes a laser device, a microscopic device, a beam splitter device and a photodetective device. By utilizing lasers with different central wavelengths or a broad band light source to simultaneously analyze THG response with respect to different wavelengths, a plurality of THG images and THG spectrum of the material or bio-tissue under stimulation of different wavelengths are obtained, thereby retrieving distributed microscopic images and resonant characteristics of the observational material or bio-molecules.