Rare earth elements (REEs) are irreplaceable in modern societies due to rising demands, especially amidst the urgent energy transition background. As the first ordered and the second most produced REE, lanthanum is widely used in conventional fields. This study investigates lanthanum flows and stocks in China by conducting a dynamic material flow analysis for the period of 2011–2020. The main results are that: 1) The registered quota production of La from 2011 to 2020 is 235,306 tons, and net La import accounts for 24.79% of the total input flows. 2) The accumulative surplus of La under the circumstance of quota production is 35,929 tons, with the in-use stock being 148,556 tons. 3) China is the net La importer of concentrates (133,769 tons) and net La exporter of primary, intermediate, and final products. The net La export is mainly in the form of primary products (76.27%). 4) The consumption of La increases steadily from 21,708 tons in 2011 to 31,580 tons in 2020. The top 5 applications are FCC (45.58%), rechargeable NiHM battery (16.97%), alloy (10.77%), optical glass (8.95%), and polishing powder (4.86%). Policy suggestions include expanding the demand market, adjusting the quota production system based on REEs, and improving investment in and guidance for R&D.