In order to grasp the local force situation of the Pearl River Bridge, the strain distribution of the box girder concrete near the anchor pad was tested during the longitudinal prestressing construction of block 17# of pier 1#, and the comparative analysis of theoretical calculation and measured value showed that the maximum longitudinal compressive strain obtained by the test was -58.96με, the maximum transverse compressive strain on the side of the anchor pad was -139.37με, and the corresponding compressive stresses were 2.06MPa and 4.88 MPa, respectively, which were much smaller than the compressive design strength of concrete. The anchoring area of the box girder is always in a flexible working state, the longitudinal strain of the box girder roof concrete is compressed, the lateral tension, the measured value is consistent with the law worth the theoretical calculation, except for the closest near the tension jack, the test strain value is in good agreement with the theoretical calculation value, within the range of 52 cm of the anchor pad, the box girder concrete is tensile longitudinally and transversely, and the force is the most unfavorable.