Coupling between the boulder needs of seawall armour structure，stone sources situation of Niyu material site was under investigation.The technical measures to improve boulder rate were analyzed.Considering the array pitch，increment pitch，stemming length and detonation mode，test was done.The result shows that the rate of stone of over 100kg is 24.2%，the rate of stone of over 800kg is 10.9%.But the seawall project also needs 0.22 million cubic stone，42.3%of the total.So， ensure safety in the high water season， optimal test is suggested to improve the utilization of stone over 300kg.