The unbonded prestressed concrete lining test section of the sediment sluicing tunnel in the Xiaolangdi Multipurpose Dam Project on the Yellow River adopted the new OVM ring-anchor unbonded prestressing technology. This paper summarizes the arrangement of prestressing tendons and measuring elements in the in-tunnel test section as well as the in-tunnel unbonded prestressed concrete construction technology. Based on the full-process field measurement of the tensioning and anchoring structure of the prestressing tendons, it analyzes the variations of concrete swelling-shrinkage and thermal stress, the stress distribution law of the in-tunnel unbonded prestressed concrete lining, presents the achievements of the in-tunnel unbonded prestressed concrete lining, and proposes improvement suggestions on optimizing the concrete mix proportion and strengthening construction temperature control.