The Shilu iron deposit is located in western section of the Wuzhishan Fold Belt, Hainan island.In this region, numerous intermediate-basic dikes dominated by diorite-porphyrite occurred. The dating of zircon from diorite-porphyrite dikes determined by LA-ICP-MS yields age of 248±1 Ma (MSWD=0.4), maybe bimodal intrusion with contemporary alkali-rich granites. Diorite-porphyrite dikes are dominated by shoshonitic rocks, which have SiO2 varying from 49.18% to 55.25%, Al2O3 from 14.36% to 16.75%, FeOt from 5.98% to 10.07% and MgO ranging from 3.80% to 5.43%. These dikes are enriched in large ion lithophile elements (LILE) and low rare earth elements (LREE) but depleted in high field strength element (HFSE).The Nb/Ta values of diorite-porphyrite vary from 15.33 to 17.80, Zr/Hf and La/Nb from 36.00 to 45.23 and 2.59 to 8.62, respectively.Two samples have (206Pb/204Pb)t=18.087-18.483, (207Pb/204Pb)t=15.473-15.589 and (208Pb/204Pb)t=38.272-38.817, similar to the data of contemporary alkali-rich granites. Geochemical and Pb isotopic compositions indicate that these dikes are possibly derived from enriched mantle and slightly contaminated with crust.Hf/3-Th-Ta and Zr-Zr/Y discriminant diagrams imply these diorite-porphyrite dikes intruded in a local nextensional tectonic setting in continental arc, caused by the Indian plate northeastern subduction to the South China Block.