Abstract: Exposed at the south of Conghua city, Guangdong province, the Lapu amphibole- and biotite-bearing monzonitic granite occupies an area of about 500 km2. The rock is composed of calcic amphibole （0.5%）, biotite （ 11 - 13% ）, plagioclase （An35 -41,29 -31% ）, cryptoperthite （24 -31% ） and quartz （36 -37% ）, carrying some amounts of Ca-, Ti-rich minor minerals such as allanite and titanite. Based on zircon U-Pb isotopic dating, the rock emplaced at 163 ±2 Ma （mid-Jurassic）. Petrochemically, the Lapu granite is weakly peraluminous （A/ NKC = 1. 043 in average） and with higher K20 content （4.72% in average）, belonging to the high-K calcic-alkaline series. The rock has high EREE contents （（ 180 -460） × 10-6）, showing an evident LREE-enriched and HREE-depleted tendency, and with higher （La/Yb）N values （19 in average）. These features indicate that partial melting of source materials for forming Lapu magma occurred at a deeper （ lower crust） level （p 〉 10 × l0s Pa） and that garnet would be a main residual phase, which resulted in HREE depletion in the melt. According to many trac- ers for source rocks （Patino Douce, 1999）, it is suggested that the source rocks for forming Lapu magma were metagreywakes or meta-amphibolites. Analyses for Sr, Nd, Pb isotopic compositions of the Lapu granite yielded a feebly high Isr （0.7124 - 0.7155 ） and lower εNd （t） values （ - 11. 18 - - 11. 54 ）. Model calculation shows that the melt formed by 55% partial melting of the lower crust rocks would have the similar geochemical features as those of real Lapu granite magma.