This report establishes the BRICS science，technology and innovation （STI）development evaluation index system and measures the STI development of BRICS countries from 2018 to 2021. Overall，among BRICS，the overall scores of China and Russia are more outstanding，meanwhile China，India and Russia show a growing trend，but South Africa and Brazil remain unchanged to some extent. In terms of first-level indicators，there is little change in the score of STI environment of BRICS，among which India and China are more prominent；In terms of STI input，China’s score has increased significantly with outstanding performance followed by Russia’s score，while India’s STI input needs to be strengthened. In terms of STI performance，BRICS show a steady growing trend，among which India rises obviously，and China scores the highest. In the aspect of STI basis，four countries except Brazil show an upward trend，with the more increases in China and India. Besides，with regard to international science and technology （S&T） cooperation，the mechanism of STI cooperation becomes more mature：closer industrial cooperation among countries；more frequent high-tech trade engagements；expanding international cooperation of research cooperation，among which materials science（interdisciplinary），astronomy and astrophysics，and physical chemistry are the core areas；S&T people-to-people exchanges have constantly deepened，with China the primary choice for students in BRICS to study abroad. In the future，we should take the BRICS membership expansion as an opportunity to uphold the concept of open，fair，just and non-discriminatory cooperation，deepen international S&T exchanges and cooperation to tackle major global issues and challenges，actively promote the reform of the global S&T governance system，and expand the influence of BRICS STI cooperation.