Abstract: Targeting the first active pile underpinning engineering in China for metro underground-excavated tunnel under-passing irregular widening continuous beam, the main monitoring items, monitoring frequency and main control values are introduced in detail. By data monitoring mode combining remote automatic monitoring and manual monitoring, and through regression analysis of the monitoring data, the variation curves of retaining piles inclination and bridge piers displacement in the whole underpinning engineering are obtained. The relationship between lift-up force and deformation during underpinning process is further analyzed. Research results show that the monitoring data of construction is within the expected range, and the deformation control effect is good. The allowable values of pier displacement for active pile foundation underpinning should be determined by considering the achievable performance with existing construction technology and equipment under normal conditions, and the structural deformation that may occur from the completion of hydraulic jack lift-up to the completion of later stage tunnel construction. The relationship between the vertical displacement of the lifted pier and the hydraulic jack loading force during hydraulic jack lift-up process is nonlinear.