The utility model belongs to the field of electric power substation building project construction, and particularly relates to an adjustable cable trench construction cover plate used for temporarily covering the trench surfaces of cable trenches of different widths. The adjustable cable trench construction cover plate comprises an outer cover plate and an inner cover plate which are lath-shaped. The inner cover plate is embedded or sleeved in the outer cover plate, and the two cover plates form a sliding fit relationship featured by movement along a fixed direction. The inner cover plate and the outer cover plate are provided with a plurality of threaded holes, the threaded holes are sequentially arranged along the movement direction of the two cover plates, and the threaded holes of the two cover plates are in fixed connection fit through bolts. The adjustable cable trench construction cover plate of the utility model is simple in structure and high in practicability, can be used for multiple purposes to meet the requirement of cable trench covering within a specified width range, and has a wider range of applications.