CPH switch laying and relaying machine is Underside unit used for the laying and replacement for the turnouts of high-speed railway, new railway and existing railway. The unit consists of a number of topside and underside units, temporary tracks and auxiliary systems; and each topside/underside unit is powered for its hydraulic system by an imported diesel engine. The advanced radio remote control system and complete security monitoring system are equipped. During the operation, the machine completes the laying and replacement for the turnout by lifting, moving horizontally or vertically and controlling the turnout components. A topside unit and a underside unit form a set, and two sets can carry out the joint operation. This kind of formation allows up to 12 sets be used for joint work, which means laying and replacement for a sect ion of turnout up to 80 m can be completed at one time.