Taking the crest wall of sloping structure as a research object,we study the wave load of crest wall under impulsive action of long-period wave by the physical model experiment,take the result of experiment to compare with the calculation results of Chinese design code and American coastal engineering manual (CEM),and adopt verification experiment to prove the obvious differences between them.The results show that China code and CEM have very close results but much smaller than that of test,with ratio of 1:5.Impulsive action of long-period wave on crest wall should be paid more attention in project design.Physical model test is indispensable for the reliability of structure,even if we can calculate by the code formulas.