Aiming at the problem of insufficient oilabsorption of hydraulic pump,an annular multinozzle auxiliary oil suction device based on the principle of jetflow was designed.Considering the size requirements and working conditions,the oil suction device with big area ratio was chose.A CFD model of the device was made,the influence of nozzle numbers,incident angle of nozzle,distance between the nozzle and throat,suction chamber angle,length of throat on the efficiency of the device were researched by Fluent.The results show that under the condition that the sum of nozzle exit area is unchanged,the nozzle number is less,the better efficiency.When the nozzle number is 2,the efficiency is best.Within a certain range,the effect of incident angle and distance between the nozzle and throat is very small,and the incident angle normally ranging between 20°~35°,and the distance need to close to inlet diameter of throat.the effect of suction chamber angle is also small,when the angle ranging between 14°~52°,efficiency of the device is almost unchanged.when the ratio of length and diameter of throat ranging between 2~25,the efficiency is better.