Aiming at the design of armor blocks at the transition between vertical and slope structures under the impact of STEM waves,we analyze existing code formulas and test data of multiple engineering cases,propose a calculation method for the stable mass of armor blocks at the transition and validate through three-dimensional physical model tests of practical projects.The results indicate that the stable mass of armor blocks under STEM waves at the transition calculated by the Hudson formula is underestimated and should be appropriately increased.When the stable mass of Chinesepodes at the transition is calculated,it is recommended that the stability coefficient KD should be 11.5,and the stable mass should be taken as 2 to 3 times the value calculated by the formula.Due to complex factors affecting STEM waves,it is suggested to verify the rationality of the design scheme of practical project through three-dimensional physical model tests.