Abstract: This paper introduces the contrastive analysis between the monitoring and computation for the scroll case concrete.We know from the analysis that although the scroll case structure is complex, and in a complex stress condition, the stress of the scroll case measured on the spot is less than the stress computed in material mechanics method and three-dimension finite element method.The maximum stress of the scroll case measured on the spot is 100.48 MPa when the water level is 135 m high, even less than half of the test stress in the simulating model test. The monitoring indicates that the scroll cases in the left-bank powerhouse work normally.