Abstract: The simulation of magma fluid flowing in and around granite plutons indicates that the top zone, apical or cupola of intrusion are the locations of focused fluids flow, where fluid flux is larger than the lateral wallrock. After the emplacement of hydrous magmas, two sequential processes play critical roles: the process of second boiling and decompression. The mechanical energy released in the second boiling exceeds the maximum tensile strength of the wallrock, which can produce extensive fracture failures. Because the axis of least principal stress in the shallow crustal environment generally lies essentially in the horizontal plan, failure of the roof rocks including the H2O-saturated carapace and wallrock produces myriad steeply dipping fractures and hydro-fracturing. The cupola and apical of magma body and the radial and concentric fracture systems, breccia pipes occurred in and around prolate magma body are structural weak zones, they can provide excellent accomodation for granite-related hydrothermal minerals. During the prospecting of hidden and concealed granite-related polymetallic deposits, it is a shortcut to explore the top zone or cupola of hidden intrusions.