The coup in Guinea is one of five military coups and attempted coups in Africa in 2021. Due to the country’s huge reserves of strategic resources such as bauxite and iron ore，its important position in raw materials supply of the global aluminum ore，it has attracted the attention of the international community among the five coups. This paper analyzes the internal factors of the coup in Guinea and the reactions of international parties，and introduces the process of political transition in Guinea after the coup，the role of regional organizations，the progress made in the transition，the current main problems and the future outlook，hoping to provide some references for the study of the coup and post-coup political transition in Guinea in 2021.