Mobile phone holder with automatic clamping function

A mobile phone holder with an automatic clamping function, comprising:

• a base and an automatic clamping mechanism disposed on the base, wherein the automatic clamping mechanism comprises a clamping arm, a gear, a one-way ratchet, a key spring, a button and a driving component for driving the gear to rotate, the clamping arm is slidably mounted on the base, a clamping space for clamping a mobile phone or a tablet computer is defined between the clamping arm and the base, the clamping arm is provided with a rack portion, the gear is rotatably mounted in the base, the rack portion is engaged with the gear, the one-way ratchet is mounted above the gear, the one-way ratchet rotates along with the gear, the key spring is elastically clamped between the gear and the one-way ratchet, an upper end of the one-way ratchet is provided with ratchet teeth, the base is provided with a clamping slot adapted to the ratchet teeth, the button is mounted above the one-way ratchet, and the base is provided with an opening through which an upper end of the button penetrates.