Abstract: “Lithium Triangle”, a junction area among Argentina, Bolivia and Chile in South America, is a hot spot for lithium mining in this era of new energy industry revolution, hence it is necessary to discuss and compare the lithium resources distribution and mining investment environment of the area, so as to provide Chinese enterprises with suggestions for investing in the local lithiummining. The paper analyzes the metallogenic geological settings, resources distribution, exploration and development of lithium mining in the study area. It’s concluded that the vocalism since Miocene provided abundant metallogenic materials, and numerous closed catchment basins were formed in the process of Pliocene tectonic subsidence, coupled with the perennial evaporation in extremely arid climate of the Andean desert, then lithium resources were accumulated and conserved in the salt lakes. The superior-quality lithium resources, featured with high content of lithium ion and low ratio of Mg/Li in the brine water, are widely distributed in the junction of Argentina, Bolivia and Chile. Based on the specific conditions of the three countries in the Lithium Triangle, this paper adopted Analytic Hierarchy Process and Linear Weighted Comprehensive Evaluation to establish an evaluation index system of lithium mining environment. Four Tier I indexes including mineral resources endowment, policy and law, social environment and infrastructure, and 11 Tier II indexes including resource grade, Mg/Li ratio, resource quantity, exploration input, lithium mining foreign policy, fiscal and tax system, restrictions on profit repatriation, inflation rate, mining conflicts, infrastructure quality and water availability were generally analyzed. By calculation, the overall score of lithium mining environment in Argentina is 0.8, Chile 0.36 and Bolivia 0.27, indicating that Argentina is the best mining target in the region, and salt lakes such as Hombre Muerto, Cauchari-Olaroz deserve investment attention. The research conclusion may practically guide Chinese mining companies’ investment choice in Lithium Triangle.