The invention relates to a cable well cover opening device, comprising a main beam, a right pillar and a left pillar with adjustable height; the main beam is provided with a turnplate, the turnplate is provided with a lifting assembly including a slider and a lifting portion, the turnplate is provided with a linear guide, the slider is disposed on the linear guide, the right pillar is provided with a pushing assembly, a horizontal transverse bar is provided with an adjusting assembly, and the turnplate is connected with a driving assembly; the cable well cover opening device has the advantages that the lifting assembly is descended to connect with a cable well cover under pushing of a telescopic bar in a first push bar, the cable well cover is quickly opened by tension produced wen the telescopic bar in the first push bar returns, and opening work intensity is effectively reduced for operators in the prior art; the lifting assembly is rotated through the turnplate, it is possible to effectively prevent a power cover plate from falling into a borehole, high safety is provided, damage degree of an edge wall of the borehole is reduced, and the life is prolonged.