The invention discloses an automatic variable load optimal control method for internal compression argon air separation equipment. The automatic variable load optimal control method is characterized by mainly considering the phenomenon of mutual influence and bad coupling among an upper tower, a lower tower, a rough argon tower, an air compressor, a pressurizer and an expander of the air separation device; a large prediction controller is adopted to realize a variable load control function of the air separation device; the air separation device includes the upper tower, the lower tower, a molecular sieve, the rough argon tower, a finish argon tower, the air compressor, the pressurizer and the expander; and the large prediction controller adopts an operation trajectory LPV modeling method with a product oxygen flow as a dispatching variable to build a variable load nonlinear dynamic model of the air separation equipment. The automatic variable load optimal control method for the internal compression argon air separation equipment effectively reduces the process variable fluctuation range in the variable load process, realizes the variable load operation more quickly and stably, reduces the oxygen emission, and realizes energy conservation and consumption reduction of the air separation equipment.