Through the wave cross-section physical model test, the wave reflection coefficient and wave crest height of the open caisson structure under irregular wave action can be measured. Through the single factor analysis method, this paper mainly analyses the influence of different factors related to the permeable upper structure to the reflection coefficient based on the study on the basic structure of open caisson structure; and at the same time analyses the influence of factors to the wave crest height in the same way. Finally, it fits out formulas to compute the two physical quantities, proving the formula about wave crest height by theory and establishing the relationship between it and reflection coefficient. The test results may serve as reference for the engineering design.