The application provides a flat threshold maintenance passage structure and an operation method. The structure comprises a large opening reinforcing structure
assembly 100, a quick-release floor
assembly 200, a footboard
assembly 300, a door frame assembly 400, a stepping reinforcing assembly 500, a mechanical support rod assembly 600, a bolt
locking mechanism 700, a maintenance passage door 800, an external hinge 900 and a boarding
handle 1000. The large opening reinforcing structure assembly 100 comprises an upper reinforcing horizontal piece 101, a lower reinforcing horizontal piece 102, a reinforcing front partition frame 103, a reinforcing rear partition frame 104, a horizontal piece outer
flange 105, a stretching belt plate 106, an upper horizontal piece inner
flange 107, a stretching belt plate 108, a lower horizontal piece inner
flange 109, a counter-pulling angle box 110 and a counter-pulling angle piece 111. The quick-release floor assembly 200 comprises an upper panel 201, an
aluminum honeycomb 202, a lower panel 203 and a bowl-shaped piece 204. The footboard assembly 300 comprises a foldable
cantilever footboard 301, a
locking mechanism 302, a bolt 303, a partition frame T-shaped outer flange 304, a support lug 305, a rib 306 and a stepping pedal 307. The door frame assembly 400 comprises a door frame 401 and a
skin 402.