A novel bore well casing and a large-wellbore multi-branch well rapid drilling and completion method using same. The casing comprises a casing wall and a plurality of sand control devices (7) spaced apart on the casing wall; each sand control device (7) comprises a sand control mesh, a sealing steel sheet (7-3), and a sealing rubber plug (7-2); a plurality of sand control screen holes (7-1) which are parallel to each other is provided on the sand control mesh; the sand control screen holes (7-1) directly face the sealing steel sheet (7-3); the sand control mesh and the sealing steel sheet (7-3) are connected by means of a steel pin (7-4). According to the method, a main wellbore (5) is formed by drilling a large-size drill bit (12) into a target well at a time, then, a branch wellbore (6) is drilled in a natural gas hydrate reservoir by using the novel bore well casing, and then, the drill bit (12) is removed for completion. The method is suitable for various natural gas hydrate exploitation modes, and the yield and recovery of a hydrate well can be greatly improved. Moreover, the well drilling and completion are integrated, thereby shortening the well drilling and completion period, and being able to realize effective sand control while saving a large amount of manpower and material resources.