The utility model relates to a continuous flow tube reactor for hydrogen preparation through photosynthetic bacteria. A main body of the reactor is a transparent spiral tube which is filled with spherical fiber fillers, a tube light source is perpendicularly arranged at the center of the spiral tube, and the spiral tube and the light source are arranged in a temperature control tank. Raw materials are delivered to a raw material preheater through a material feeding pump for heating, and then enter the main body of the reactor for photosynthetic hydrogen reaction. Hydrogen is separated through a gas-liquid separator, liquid at the bottom of the separator is absorbed back to the main body through an A backflow pump, some liquid is absorbed back to a bacteria liquid sedimentation tank, supernatant liquid in the bacteria liquid sedimentation tank is discharged through an overflow opening, liquid in the lower portion of the bacteria liquid sedimentation tank is absorbed back to the main body of the reactor through a B backflow pump, and the whole reactor adopts a closed system. The tube reactor resolves the problem of low utilization ratio of the existing reactors, fully utilizes illumination condition, provides larger light receiving area, and benefits bacterial growth to form a flora advantage, thereby increasing hydrogen preparation efficiency finally.