The invention discloses a tubular opening component protection device for a spacecraft. The protection device is of a tubular structure with the lower end opened and is composed of two protection halfboxes, hinges, a spring bolt and a boss. One ends of the two protection half boxes are connected through the two hinges, closing and opening can be achieved through the hinges, and the other ends ofthe two protection half boxes are firmly connected through the spring bolt and the boss. The opposite faces of the two protection half boxes are symmetrically provided with sealing strips. Two sets oftight holding rings are symmetrically arranged on the inner sides of the two protection half boxes and are used for tightly clamping a protected piece, and meanwhile the radial sealing function is achieved. The tubular opening component protection device can be widely applied to spacecraft tubular opening component protection, plastic materials are adopted, and the protected piece cannot be damaged. The sealing strips have sealing and protecting functions on the whole device, and extra materials can be reliably prevented from entering the protection device. The spring bolt and boss tight buckling fastening manner is adopted, operation is convenient for a user, the hinges can meet the long-service-life requirement, and opening is convenient and fast.