The invention discloses a light path continuously adjustable catalyst dynamic structure in-suit representation device. According to the light path continuously adjustable catalyst dynamic structure in-suit representation device, the upper side of a front cover (11) is provided with a long groove type horn mouth; a fixed window flake (1) is arranged on the upper end surface of a fixed window flake pedestal (4); a movable window flake (3) is embedded in the upper end surface of a movable window flake pedestal (7); the movable window flake pedestal (7) is provided with a through hole in the axial direction; the movable window flake pedestal (7) is immobilized in the fixed window flake pedestal (4); a sample cabin (2) is formed among the fixed window flake (1), the fixed window flake pedestal (4), and the movable window flake (3); the fixed window flake pedestal (4) is provided with two axial circular holes, and is communicated with the sample cabin (2); an inlet pipe (5) and an outlet pipe (10) are inserted into the two axial circular holes respectively; a flat backing ring (6) is arranged between a back pressing ring (8) and the movable window flake pedestal (7); the back pressing ring (8) and a back pressing pedestal (9) are connected via screw threads; a back cover (9) and the front cover (11) are firmly connected via bolts. The light path continuously adjustable catalyst dynamic structure in-suit representation device is capable of realizing catalyst dynamic structure in-suit one-line representation, accurate is high, and application range is wide.