The invention discloses a variable-capacity rigid collection chamber for a spacecraft integral leak rate test. The collection chamber comprises a collection chamber cavity and a collection chamber front door arranged on the side wall of the cavity, a detachable partition plate is arranged in the collection chamber cavity, an O-shaped solid sealing ring is arranged in the circumferential direction of the portion between the partition plate and a fixed ring beam on the side wall of the cavity, a movable beam is arranged on the side face, opposite to the front door, of the partition plate so that the movable beam can move to the top of the collection chamber cavity after the partition plate is detached, the movable beam is arranged below the partition plate, the contact faces between the two ends of the movable beam and the fixed ring beam are 45-degree bevels, the bevels are sealed through sealant, fixing supporting columns are arranged at the bottom of the movable beam, an inflatable sealing ring is arranged on the whole body of the front door in the circumferential direction, and the cavity can be sealed through a square inner door frame welded to the collection chamber and the inflatable sealing ring. Due to the overall inner door frame mode, the weight of the front door is reduced to a large extent, and the front door can be opened more conveniently.