There are many difficulties in dealing with water and sand gushing in construction of connection gallery of rivercrossing tunnel. The excavation and supporting of No. 3 connection gallery of Ganjiang Rivercrossing tunnel on Line on of Nanchang Metro have been successfully completed by summarizing the site construction experience and improving the grouting method. The construction practice shows that the construction technologies adopted are suitable for tunneling in moderately weathered argillaceous siltstone strata.