The invention provides a monitoring device and a monitoring method for bridge deck construction layout. The monitoring device comprises a bottom plate, fixed frames which are vertically fixed to the two sides of the top of the bottom plate, a sliding plate which is transversely arranged between the two fixed frames and connected with the fixed frames in a sliding mode, a fixed box which is locatedbelow the sliding plate and fixed to the top of the bottom plate, a central processing system and a data monitoring and processing system, wherein the data monitoring and processing system is arranged at one side of the top of the sliding plate, and a monitoring camera is fixedly connected to the other side of the top of the sliding plate. The invention relates to the field of bridge deck construction technologies. Through the monitoring device, interference of external vibration is reduced during movement monitoring; and meanwhile, it can be convenient to adjust the height of the monitoringdevice, and much convenience is provided for staff.