Amplitude modulation type security saw

The invention discloses an amplitude modulation type security saw which is composed of a shell, a driving mechanism, an amplitude modulation mechanism, a saw blade clamping device and a telescopic saw bow. A motor in the driving mechanism drives an eccentric pin through synchronous belt drive and gear drive as crank motion; the eccentric pin, a slider A, a chute, a short slide shaft and a short slide shaft support form a crank double-slider mechanism, and the short slide shaft is driven to linearly reciprocate through the eccentric pin; the amplitude modulation mechanism is capable of amplifying or lessening motion amplitudes of the short slide shaft by adjusting an amplitude modulation shaft in position and transmitting the motion amplitudes to a long slide shaft; a saw blade is mounted at one end of the long slide shaft through the saw blade clamping device which drives the saw blade to linearly reciprocate. The telescopic saw bow can be adjusted in telescopic length according to application scenarios, and the saw blade is well guided and supported through a pulley.