Abstract: The mafic dikes in Guangdong Daba Rock Mass is distributed with NWW trending and near EW trending.Based on rock sampling analysis results of the study area,the geochemical characteristics and genesis of the mafic dikes in Dam Rock Mass in Guangdong Province are studied in detail.The study results show that:the main elements of the mafic dikes show that it is belongs to intraplate tholeiite and calc-alkali series;the trace elements are rich in large ionic lithophile elements K,Rb and Th,and lack of Ba,Sr,Zr,Nb and Ti;the fractional distillation characteristics of rare earth elements in rock samples is not obvious,the light rare earth element is slightly enriched,Eu anomaly is not existed basically,which is similar to intraplate basalt;the TiO2 contents of the mafic dikes is closely similar to the one of basalt of lithospheric mantle;the ratio of trace element elements show that trace elements is derive from the mantle source region that the trace elements is enriched relatively;the rock genesis is belongs to the stretching production of weak tectonic belts after plate subduction.