Disclosed herein is a floating ball filling-control device for a cryogenic tank with enhanced structural stability. The floating ball filling-control device comprises a liquid feeding pipe (2) with a liquid discharging end disposed in the liquid storage tank (1), the liquid feeding pipe (2) having liquid spraying holes (3) located on the pipe wall at the top of the pipe, and a slide valve (4) arranged on the top end of the liquid feeding pipe, wherein the slide valve is in a sliding fit with the liquid feeding pipe in a vertical direction via a floating ball lever driving mechanism, and forms an open/close mechanism for the liquid spraying holes via a control mechanism.