The invention discloses a film thickness and refractive index simultaneous measurement device and measurement method and belongs to the optical measurement field. The measurement device specifically includes a wide-spectrum light source output module, a narrow-linewidth laser light source output module, a film thickness measurement probe module, a demodulation interferometer module, and an acquisition and control module. According to the film thickness and refractive index simultaneous measurement device and measurement method of the invention, the output signals of the narrow-linewidth laserlight source output module are directly inputted into the demodulation interferometer module, and therefore, interference signals can share the same optical path, and at the same time, the influence of the transmitted light of laser and the multiple-reflected light of the laser in the film thickness measuring probe module on the quality of the interference signals can be avoided; and the length ofthe pigtails of a film thickness measuring probe can be controlled, so that the interference of the transmitted light of wide-spectrum light in the film thickness measurement probe module on characteristic signal peak identification can be avoided. With the film thickness and refractive index simultaneous measurement device and measurement method of the invention adopted, the non-contact measurement of the thickness and refractive index of a film can be realized with the calibration of a calibration sample not required. The film thickness and refractive index simultaneous measurement device and measurement method have the advantages of self-calibration, traceability of measurement results, high stability, simplicity in characteristic signal identification and the like.