Abstract: This article deals with the reinforcement method of pouring high-pressure non-dispersive mortar into the underwater riprap of piers as well as the research on the comprehensive effectiveness detection of the method.Non-destructive examination methods are used such as ground penetrating radar,elastic wave CT,wave velocity and point loading strength of the rock core specimens.It is seen from the research results that it is a reliable and effective method to reinforce underwater riprap by pouring into the underwater riprap a certain quantity of high-pressure grout, which is blended in the proper ratio of sand and cement with a certain quantity of underwater non-disperser,and that elastic wave CT and ground penetrating radar can be employed in the effectiveness detection of the reinforcement by underwater high-pressure grouting.In addition, these detecting methods can also be applied to the effectiveness detection of the high-pressure grouting in other usages.