The BF3/n-BuOH complexes were investigated as active species in catalyzing n-decene polymerization reaction. The structures of BF3/n-BuOH complexes were characterized not only by modern spectrum but also by calculation at theoretical level. The results confirmed that BF3/n-BuOH complexes changed from BF3 center dot (n-BuOH)(2) complexes to BF3 center dot n-BuOH complexes with the mass fraction of BF3 increasing. These two complexes have different catalytic activity, but BF3 center dot n-BuOH was superior. The highest n-decene conversion could reach 99% and the most excellent selectivity of n-decene trimer and tetramer could reach up to 80% yield by a series of controlled conditions. This work can help to understand the catalytic active species of n-decene polymerization and provide support for industrialization of poly-alpha-olefins (PAOs). (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.