The construction scheme for the cutting of the piles inside tunnel in the active pile foundation underpinning on Line 2 and Line 8 of Guangzhou Metro is presented. Cutting the piles inside the tunnel in active underpinning is a new approach of pile foundation underpinning, which absorbs some part of the construction methods of the passive pile foundation underpinning. Due to the new underpinning approach, the problem that it is very difficult to balance the horizontal forces during the underpinning of the operating curvilinear bridge is solved. The construction methods of underpinning under dynamic loading conditions and the monitoring of the bridge structure during underpinning are described. The works practice provides experience for the pile foundation underpinning of complex structures under complex geological conditions in the future.