The utility model provides a shield tunnel pedestrian walkway plate support adjusting device. The adjusting device comprises a first L-shaped supporting plate, a second L-shaped supporting plate, a nut and an adjusting bolt. A transverse plate of the first L-shaped supporting plate is arranged above a transverse plate of the second L-shaped supporting plate; welding fixation, a clamping groove clamped with a human walking road plate bracket is formed between the vertical plate of the first L-shaped supporting plate and the vertical plate of the second L-shaped supporting plate; bolt adjustingholes are correspondingly formed in the overlapped fixing parts of the transverse plates of the first L-shaped supporting plate and the second L-shaped supporting plate, nuts are fixed to the positions, corresponding to the bolt adjusting holes, of the upper portion of the transverse plate of the first L-shaped supporting plate, and adjusting bolts are inserted into the bolt adjusting holes from the bottom face of the transverse plate of the second L-shaped supporting plate and are in threaded connection with the nuts. The adjusting device provided by the utility model can simply and effectively adjust the placing posture of the pedestrian walkway plate bracket, provides a straight pedestrian walkway plate laying condition, and ensures that the pedestrian walkway plate of the shield tunnelis straight, safe and attractive.