The invention relates to tea leaf picking machinery and aims to provide a differential speed type tea leaf picking mechanical arm. The mechanical arm can simulate human hand tea leaf picking actions to perform tea leaf picking to achieve lossless tea leaf picking. According to the technical scheme, the differential speed type tea leaf picking mechanical arm comprises a support rack, a tea leaf collecting box and a tea leaf picking mechanism, wherein the tea leaf collecting box is fixed to the lower portion of the support rack, and the tea leaf picking mechanism is mounted on the support rack;the tea leaf picking mechanism comprises a motor, a planetary gear train, a drive finger, a driven finger and an air pipe, the motor is fixed to the lower portion of the support rack, the planetary gear train is driven by the motor, the drive finger and the driven finger are driven by two planetary gear shafts in the planetary gear train, and the air pipe jets air to collect tea leaves.