A thumb mechanism, comprising: a linear direct drive motor comprising a motor shaft and a motor device, wherein the motor shaft is arranged in the motor device, the motor device is arranged onto a bottom bar, a front pivot hole of motor is arranged at a motor shaft front end, a rear pivot hole of motor is arranged at a free end of the motor device, and a front pivot hole and a rear pivot hole are respectively arranged at two free ends of the bottom bar, and wherein the rear pivot hole of motor and the rear pivot hole on the bottom bar are used to pivotally connect the motor device to the bottom bar; a thumb first connecting bar provided with a first pivot hole at a front end, a second pivot hole at a middle part, and a third pivot hole at a rear end thereof, wherein the second pivot hole and the front pivot hole of motor are used to pivotally connect the thumb first connecting bar to the motor shaft front end, and the third pivot hole and the front pivot hole are used to pivotally connect the thumb first connecting bar to the bottom bar; a thumb second connecting bar provided with a fourth pivot hole at a front end and a fifth pivot hole at a rear end thereof, wherein, by means of the fifth pivot hole and the first pivot hole, the thumb second connecting bar is pivotally connected to the thumb first connecting bar; a thumb drive bar provided with a sixth pivot hole at a front end and a seventh pivot hole at a rear end thereof, wherein, by means of the seventh pivot hole and the second pivot hole, the thumb drive bar is pivotally connected to the thumb first connecting bar; a thumb metacarpophalangeal joints member provided with a pair of eighth pivot holes at a front end and a ninth pivot hole at another end thereof, wherein by means of the ninth pivot hole and the sixth pivot hole, the thumb metacarpophalangeal joints member is pivotally connected to the thumb drive bar; and a thumb finger member provided with a tenth pivot hole at an upper end thereof and an eleventh pivot hole at one end of a side adjacent to the thumb metacarpophalangeal joints member, wherein, by means of the tenth pivot hole and the fourth pivot hole, the thumb finger member and the thumb second connecting bar are pivotally connected to each other, and, by means of the eleventh pivot hole and the pair of eighth pivot holes, the thumb finger member and the thumb metacarpophalangeal joints member are pivotally connected to each other. a linear direct drive motor comprising a motor shaft and a motor device, wherein the motor shaft is arranged in the motor device, the motor device is arranged onto a bottom bar, a front pivot hole of motor is arranged at a motor shaft front end, a rear pivot hole of motor is arranged at a free end of the motor device, and a front pivot hole and a rear pivot hole are respectively arranged at two free ends of the bottom bar, and wherein the rear pivot hole of motor and the rear pivot hole on the bottom bar are used to pivotally connect the motor device to the bottom bar; a thumb first connecting bar provided with a first pivot hole at a front end, a second pivot hole at a middle part, and a third pivot hole at a rear end thereof, wherein the second pivot hole and the front pivot hole of motor are used to pivotally connect the thumb first connecting bar to the motor shaft front end, and the third pivot hole and the front pivot hole are used to pivotally connect the thumb first connecting bar to the bottom bar; a thumb second connecting bar provided with a fourth pivot hole at a front end and a fifth pivot hole at a rear end thereof, wherein, by means of the fifth pivot hole and the first pivot hole, the thumb second connecting bar is pivotally connected to the thumb first connecting bar; a thumb drive bar provided with a sixth pivot hole at a front end and a seventh pivot hole at a rear end thereof, wherein, by means of the seventh pivot hole and the second pivot hole, the thumb drive bar is pivotally connected to the thumb first connecting bar; a thumb metacarpophalangeal joints member provided with a pair of eighth pivot holes at a front end and a ninth pivot hole at another end thereof, wherein by means of the ninth pivot hole and the sixth pivot hole, the thumb metacarpophalangeal joints member is pivotally connected to the thumb drive bar; and a thumb finger member provided with a tenth pivot hole at an upper end thereof and an eleventh pivot hole at one end of a side adjacent to the thumb metacarpophalangeal joints member, wherein, by means of the tenth pivot hole and the fourth pivot hole, the thumb finger member and the thumb second connecting bar are pivotally connected to each other, and, by means of the eleventh pivot hole and the pair of eighth pivot holes, the thumb finger member and the thumb metacarpophalangeal joints member are pivotally connected to each other.