The mechanism to form HD+2，H+3 and D+3 from RF ion source is analyzed by experimental study of the interaction of these ions with solid foils. The structural pattern of HD+2 and the mean internuclear separations are determined using the Coulomb explosion technique. In our experiment，there is no line-shaped structure for HD+2. A theoretical model to deal with the wake effect of three-body Coulomb explosion is proposed and applied to the interaction of HD+2，H+3 and D+3 with solid foils. The model is proved to be successful and the structure of HD+2 is confirmed.