Abstract: Hydrocarbon vapor recovery technology of oil tank with ejector pump is investigated from three aspects, technological process, selection of technical parameters and structure calculation of ejector and so on.Influence factors of ambient temperature, intake pressure of low-pressure vapor, pressure of high-pressure power vapor on hydrocarbon-recovery efficiency of oil tank is analyzed.Compared with compressor, ejector pump recovery facility has characteristics of low energy consumption, simple structure and convenient care, which can substantially cut down the cost of hydrocarbon vapor recovery for oil tank and increase economic profits.