Fengjiashan Reservoir is the first engineering by successfully using measures of cavitation control by aeration to avoid the cavitation damage of water release structuree in China.The same as Fengjiashan dam, Ducky Cheuck hydropower station is the medium-sized engineering whose maximum dam height is 62.6 meters, so it is necessary to discuss the problem of cavitation and cavitation damage of the spillway chute .Used the classic algorithm put forward by Shi Qisui to calculate the critical ridge height of aerated bucket and the specification of cavitation damag , through theoretical calculation and the practical analysis ,it shows that ① it is unnecessary to set up aerated bucket on the chute of spillway; ②by controlling the construction irregularity according to the specification can effectively avoid cavitation and cavitation damag although in the case of no measures of cavitation control by aeration.