Metal-organic framework MIL-100(Fe) evacuated under different temperatures were used as catalysts for selective ethylene tetramerization with alkylaluminum cocatalysts in a laboratory slurry reactor to obtain C-8 alkanes, possibly as gasoline additives contributing to octane number. Depending on evacuation temperature, the surface area, the content of Fe-II and Fe-III coordinatively unsaturated sites of MIL-100(Fe) both changed, which were found to be three main factors affecting oligomerization performance. MIL-100(Fe) evacuated at 250 degrees C with intact pore structure and high rate of Fe-II sites reached the maximal catalytic activity of 1.26 x 10(5) g/(molFe.h), and more than 80% of products were C-8 mainly comprising branched and ringed alkanes. The high C-8 selectivity was not attributed to the steric hindrance of the pore structure of MIL-100(Fe) but the nature of metal sites. The cocatalysts had obvious influence on oligomerization performance via scavenging capacities rather than chain transfer processes through alkylation.