The invention relates to a double prerotation air intake guide blade of a cross flow fan, which belongs to the technical field of impeller machinery and comprises a positive prerotation guide blade group and a negative prerotation guide blade group, wherein the positive prerotation guide blade group comprises a plurality of air intake guide blades and the negative prerotation guide blade group comprises a plurality of air intake guide blades, the air intake guide blades of the positive prerotation guide blade group are sequentially arranged from to the end part of a volute of an air inlet of the cross flow fan to the center of the air inlet of the cross flow fan, and the air intake guide blades of the negative prerotation guide blade group are sequentially arranged from the end part of a volute tongue of the air inlet of the cross flow fan to the center of the air inlet of the cross flow fan. The invention can improve the local air intake condition of the cross flow fan and increase the operation efficiency of the cross flow fan as well as expand the stable operation working condition range of the cross flow fan, has simple structure, and can be conveniently arranged on various ventilated cross flow fans.