The utility model belongs to the technical field of nuclear power foreign matter prevention, and particularly relates to a detachable steam generator access hole movable cover plate fixing device. Theshaft pin penetrates through the shaft pin fixing gasket, the cross rod and the movable cover plate from top to bottom, and the bottom is welded with the movable cover plate; the fixed claw I and thefixed claw II penetrate through holes in the movable cover plate, extend out of the movable cover plate and are symmetrically and reversely arranged at the tail end of the cross rod; grooves are formed in the transverse ends of the fixing claw I and the fixing claw II, and the transverse rod can be screwed into the grooves of the fixing claw I and the fixing claw II; the fixed claw I and the fixed claw II are longitudinally slotted; a shaft shoulder bolt hole I and a tightening bolt mounting groove I are formed in the left side of the cross rod, a shaft shoulder bolt hole II and a tighteningbolt mounting groove II are formed in the right side of the cross rod, and two tightening bolts are mounted in the tightening bolt mounting groove I and the tightening bolt mounting groove II in the two ends of the cross rod respectively. The steam generator fixing device is easy and convenient to install, operate and maintain, the steam generator can be effectively fixed in the operation period after being installed, erosion and corrosion are resisted, and disassembly is convenient in the overhaul period.