Following the granite porphyry veins had been exposed by drilling in the 80's of the last century，the thick rock veins and main rock mass were successively discovered in ZK153101, ZK14827 drillings hole after 2007．The authors made zircon SHRIMP U－Pb dating of the Laochang granite porphyry for finding out the age of concealed granite porphyry，which yielded weighted average age of(44.6±1.1)Ma．This shows the crystalline age of the Laochang granite porphyry．The ages of the inherited coreis（529.3±13）Ma，it reflects the age of source rock．The chronology data shows that the granite porphyry is formed in Eocene and it is mineralization mother rock of Mo ore body．The diagenesis and mineralization of the Laochang granite porphyry took place in the main collision stage of the Cenozoic intracontinental collision orogenics，which fits very well with the Metallogenic peak period of porphyry type deposits in the three-river area．This suggests that there are porphyry type deposits in the west of the Lancang River fault．