Despite the occurrence of promising pegmatite deposits in the Altay of Xinjiang, West Kunlun and the Songpan- Ganzi metallogenic belt, Western China, it is difficult to find a good geological outcrop because of the serious denudation or quaternary coverage. In this study we have investigated the Rixike deposit in the Jiajika mining area as test case to address the above challenge. We have applied an innovative 1∶2000 mapping technique involving “three determinations and two references” for the blocks of pegmatite ie. determined the type, scale and density of pegmatite transformation to characterize the occurrence and topographic conditions of pegmatite vein in the mining area—a large scale mapping strategy referred to as the “3D2R- BP” method. The resulting preliminary determination of the type, occurrence and scale of pegmatite vein in the quaternary covered area provided a basis for the deployment of drilling equipment. Following confirmatory data from the drilling holes, sixteen granitic pegmatite veins, including ten spodumene- bearing pegmatite veins, have been identified in the quaternary covered area of the Rixike. This study has not only proved the applicability of the “3D2R- BP Mapping” method, but also provided a breakthrough in the exploration of new deposits. In addition, this method is also applicable to the Keryin ore field in locating and deep mining of pegmatites under quaternary coverage. In 2019, more than 150000 tons of lithium resources have been added through the project “Comprehensive investigation and evaluation of large- scale resource base of lithium beryllium polymetallic in Songpan- Ganzi lithium belt” demonstrating the wider applicability of this method.