The effects of varying intensity on the simulation of the merging of binary tropical cyclone (TC) Lionrock (2010) and Namtheum (2010) are studied using the HWRF (Hurricane Weather Research and Forecast System) mesoscale model. It is shown that the model reproduces well the intensity, track, and merging features of two TCs. Detailed analyses of the control experiment show that the intensity of Lionrock was stronger than that of Namtheum and attracted Namtheum significantly; a connected relatively high energy and water vapor channel, which linked the circulations of Lionrock and Namtheum, existed in the west of the two TCs. In the merging process of two TCs, Lionrock destroyed Namtheums structure. The rainbands of Namtheum merged with those of Lionrock. Sensitive experiments indicate that the intensity of Lionrock weakens, but the intensify of Namtheum strengthens; the two TCs still rotates and attract each other, but the merging direction is inversed.