Abstract: he Laowangzhai superlarge type gold deposit of the northern Ailao shan structure zone. Yunnan Province, is a typical example where lamprophyres are temporally and spatially related to gold mineralization. The ages of lamprophyres are in the range of 22.7-49.0 Ma. They can be subdivided into minettes and kersantites according to mineral assemblage. Major elements show that rocks are alkalic series and potassic and potassium rich calc-alkaline lamprophyres. Chondrite-normalized transitional element patterns of lamprophyres are “W” shaped which suggests that the rocks be mantle derived. MORB normalized incompatible element patterns are “camelbump” shaped which are relatively enriched in large ion lithophile elements (LILE) and high field strength elements (HFSE), and have high 85Sr／86Sr (0.70694-0.70769) but low 143Nd／144Nd(0.812488-0.51 2493) ratios. All the characteristics mentioned above suggest that the source of lamprophyres in Laowangzhai gold deposits area he abnormal (rich) mantle. The REE parameters of lamprophyres are ZREE 130.19-357 75×10^-6, LREE (l5.80-342 41×10^-6, HREE 12.64-l6.4l×l0^-6, LREE／HREE 8.10-21.92, and the chondrite normalized REE patterns are LREE-rich types. According to the REE contents, all lamprophyres may be subdivided into two groups: the high -ΣREE group with ΣREE 236.84-357.75×10^-6, LREE 220.43-342.41×l0^-6, HREE l5.15 -16.4l×10^-16, LREE／HREE 13.43-21.93: and the low -ΣREE group which have ΣREE 130.19-177.84×10^-16, LREE l15.80-163.81×10^-16,HREE 12 64-l5.01×10^-6, and LREE/HREE 8.10-11.96. Two groups of rocks are similar in the REE patterns. Modelling calculation of representative samples YD -20 (high -ΣREE )and YLW –21 (1ow-ΣREE) shows that two groups of lamprophyres in Laowangzhai gold deposit area are the products of different partial melting degrees (high -ΣREE is 7.5± and low -ΣREE is 1 3± ) of a common REE rich metasomatic mantle. The geological and structural development histroy of western Yunnan. Sr and Nd isotopic compositions, the patterns of incompatible elements and linear programming calculation indicate that the fluid form ed by dehydration of submarine sediments which were rich in ALK. LREE and incompatible elements and carried to mantle wedge by subducting plate is the major factor giving rise to formation of metasomatic rich mantle in the area.