The invention discloses a mechanical-arm material unloading method. The mechanical-arm material unloading method comprises the steps that step(1), the bottom of a bottom disc rack is provided with X-axial-direction moving idler wheels, and the outer side of the bottom disc rack is provided with an X-axial-direction moving motor; step(2), the outer end of an arm rod is connected with a lifting screw sleeve, and the lifting screw sleeve is arranged on a lifting screw rod in a sleeving manner; step(3), two loosening wheels are squeezed to open, and the loosening wheels push a loosening wheel installation rack to move towards the outer side, so that a conical head of the loosening wheel installation rack squeezes a transmission rod to move towards clamping eccentric wheel rotating shafts, a ratchet pawl arranged at the end portion of the transmission rod is arranged on a ratchet wheel in an inserted manner, meanwhile, clamping eccentric wheels clamped on strip plates are also driven to rotate and open, the clamping eccentric wheels drive the clamping eccentric wheel rotating shafts to rotate, then a mechanical arm is controlled to move backwards, and when the mechanical arm moves backwards, because the ratchet wheel on the clamping eccentric wheel rotating shafts is limited by the ratchet pawl, the clamping eccentric wheels cannot rotate with the strip plates, namely the two clamping eccentric wheels are pulled out from the strip plates maintaining an open state.