In steam cracking for ethylene process, a large number of high value-added C₄/C₅ fractions are produced. Currently C₄/C₅ fractions are processed in butadiene extraction unit, MTBE/butene-1 unit and C₅ separation unit. The by-products from the above-mentioned units such as the alkyne-containing butadiene tail gas, butadiene heavy component and C₄ raffinate from butadiene unit, the residual C₄ from MTBE/butene-1 unit and the C₅ raffinate from C₅ separation unit are not fully utilized. After continuous exploration and development by domestic research institutes, the process technologies for processing the above-mentioned resources have been improved and industrialized, and the comprehensive benefits have been further improved.