A magnetic coding free pin type lock cylinder structure includes: a lock cylinder housing (101), a lock knob (104) disposed within the lock cylinder housing (101), a lock cylinder front end over (102) and a lock cylinder rear end cover (103). Pin vertically moving grooves (114) and pin horizontally rotary grooves (113) are provided on an inner wall of the lock cylinder housing (101). An unlocking hole (116) for a magnetic coding key (115) is provided on the lock knob (104). A plurality of pm vertical sliding grooves (112) is provided on an outer wall of the lock knob (104). Free pins are provided in at least one of the plurality of pin vertical sliding grooves (112), and the free pins are big pins (107) or small pins (108).