The invention provides a float coupling device and a casing running method. The device comprises a shell body, a pressing cap and a soluble blind plate are arranged in the middle of the shell body. The pressing cap is of a hollow structure, and the lower end face of the pressing cap is connected with the soluble blind plate. According to the float coupling device, the soluble blind plate structure is adopted to replace an existing inner slide sleeve structure, the structure is simple, removal drilling is not needed, smooth running of a casing can be achieved, the risk that a float shoe circulating hole of the rear end of a float collar is blocked is avoided, and following well cementation construction is not influenced.