The application conditions and protection mechanism of soft mattress are different from the permeable frame.In order to give a full play of the advantages of both,we put forward the joint structure for the bottom protection.Studying the protective effect of the submerged breakwater by the water tank test,and analyzing the economic efficiency of the joint bottom protection,we get to the conclusion that the joint structure can weaken effectively the local scour at the edge of the bottom protection.To achieve similar effects of bottom protection,the joint bottom protection can save project investment of more than 5%.