The invention relates to a femtosecond laser film micro-nanomachining real-time monitoring device. The device comprises a laser generating system, an external light path system, a PC (poly carbonate) machine and a three-dimensional mobile platform, wherein laser sent by the laser generating system is focused on a focusing mirror through the external light path system; the device is also provided with a spectrum focusing mirror, a fiber optic probe, a spectrometer, an enlargement mode CCD (charge coupled device) and a time delay controller, wherein the spectrum focusing mirror and the fiber optic probe are fixed on the three-dimensional mobile platform; the spectrometer is connected with the fiber optic probe through data lines, and the spectrometer is also connected with the time delay controller through the data lines; and the time delay controller is connected with a femtosecond laser through a signal wire, and the femtosecond laser, the enlargement mode CCD, an optical gate and the three-dimensional mobile platform are connected with the PC machine through the signal lines. The device provided by the invention has the advantages that the equipment is simple, the operation is easy and simple, the applicability is wide, the film micromachining rapid detection is realized, the accuracy for detecting element is very high, the device almost can detect any element, and the detection efficiency and the reliability are greatly improved.