Abstract: The prestress loss of the web for a prestressed concrete continuous rigid frame bridge was studied． The phased accurate measurement of the prestress loss of the web rebars for No. 3 pier was also carried out by the embedded anchor dynamometer; meanwhile the analysis of the prestress loss was done using theoretical calculation method，whose results were compared with the measured ones． The results showed that the measured values of the prestress loss were larger than the theoretical ones，showing an underestimate of the prestress loss in the design phase． Besides the actual prestress loss was larger due to the influencing factors，such as manpower，materials during construction，which would result in adverse effects on late use of the bridge． Hence the observation of late deformation of such sort of bridge should be conducted．