The invention discloses a carrier rocket liquid oxygen filling system and relates to the field of low temperature medium filling systems. The carrier rocket liquid oxygen filling system comprises a rotary filling module, a pressurizing module, a first liquid oxygen fixing tank, a second liquid oxygen fixing tank, a third liquid oxygen fixing tank, a fourth liquid oxygen fixing tank, a first filling module, a second filling module, a third filling module, a first external storage box, a second external storage box, a third external storage box, a fourth external storage box, a fifth external storage box, a sixth external storage box, a first discharge system, a second discharge system and an evacuation port. According to the carrier rocket liquid oxygen filling system, an extruding and pumping combined filling method, a redundancy design, a liquid oxygen safe discharge technology, a multi-loop simultaneous filling technology, a high-flow supercooling technology and a one-to-many pressurizing technology are adopted; the carrier rocket liquid oxygen filling system ensures liquid oxygen filling flow and rocket entering quality as well as safety and reliability of equipment and pipelines; meanwhile, the reliability and safety of the liquid oxygen filling system are improved, and the overall requirement on the liquid oxygen filling system is met.