Sn-Nb-Ta mineralization in Limu, a tipical huge ore field in Nanling Range, has close relation to granitic diagenesis. Zircon SHRIMP U-Pb dating of mineralized granite in concealed Shuiximiao stock was eom- ducted in this paper, yielding an age of 212.3± 1.8 Ma(98% confidence, MSWD=1.5 ). The result is well consis- tent with those ages from greisenized granite in laohutou district (214.1 Ma), muscovitilized granite in Jinzhuyuan (212.4 Ma, 214.0 Ma) and sangehuangniu granite (218.3 Ma) in error range. Compiled with other references,it's clear that both Sn-polymetallic deposit and granitic stocks in Limu ore-field are production of Indosinian diage- netic and metallogentic activities in this region. As known by geologists in Nanling range, fruitful exploration chievements have been harvested in the vicility of contacts of Indosinian granites, so more attention must be paid on the exploration and evaluation in this region in next few years.