Dissolved hole of the feldspar is one of the most important pore types in volcanic rocks which accounts for 1.24% to 60.61% of all and plays an important role in reservoir. The authors analyzed the selective dissolution of plagioclase in aspects of petrography, petrochemical CIPW standardized mineral composition and thermodynamics. Petrographic features have clearly indicated the existence of selective dissolution, anorthite dissolves while albite doesn’t, at the same time when plagioclase dissolves, albite and orthoclase grows. Selective dissolution of plagioclase has been supported by the evidence of CIPW standardized mineral composition where the most end-member composition of plagioclase is albite and orthoclase, anorthite content is close to 0. It is further validated by thermodynamics study that under the same temperature, pressure and fluid conditions, anorthite is firstly dissolved within plagioclase. Deposition of albite and orthoclase happens when Na+ and K+ saturates in fluid. At this time, when plagioclase dissolves, albite and orthoclase grows.