The invention discloses an automatic grinding machine for workpiece edges. The automatic grinding machine comprises a machine case, a machine case cover, a distribution box, a control panel, a power line, a storage battery, a rack, a transverse sliding mechanism, a first motor, a vertical sliding mechanism, a second motor, a machine head, a third motor, a grinding tool, an infrared sensor, a single chip microcomputer, a circuit breaker, an alarm, a waste chipping collection device, a push mechanism, an angle adjustment mechanism and a clamping device; the machine case cover is welded to the periphery of the outer side of the top of the machine case, a workpiece can be adjusted to be at the appropriate angle after being clamped and fixed, rotation is firstly carried out to release a lockingbolt, then an adjusting plate is rotated to drive the clamping device to conduct left-and-right angle adjustment, the angle of the workpiece can be subjected to left-and-right adjustment, a pointer points to the number of degrees of a scaleplate, the workpiece adjusting angle can be quickly understood, and therefore the problems that after the workpiece is clamped and fixed, the left and right angles cannot be changed, the flexibility is insufficient, and the work efficiency is low are solved, and the flexibility and work efficiency are increased.