The invention provides an automatic PE plastic cast film slitting machine and technology. A base, an installing frame, an unreeling shaft, a tensioning mechanism, a slitting mechanism, a winding mechanism and a drive mechanism are included. The automatic PE plastic cast film slitting machine is provided, and the following problems that a, when a cast film slitting machine is adopted for slitting acast film, an unreeling shaft and a reeling shaft rotate at the same time under the action of a motor, the cast film is likely to wrinkle and roll when not slit, consequently, uneven cutting or inclination can happen after cast film slitting, and the slitting effect is influenced; and b, according to cast films with different required sizes, different cutter devices commonly need to be replaced for the existing slitting machine, accordingly, the needed-specification cast film is adjusted, consequently, slitting devices different in specification need to be manufactured, cost is high, and efficiency is low, wherein the problems exist in the PE plastic cast film slitting process.