Abstract: A vehicle-mounted mobile phone holder includes a holder body, and a fixing base, the fixing base is connected with the holder body and cooperates with a slot for placing water cup on the side of the driving position. The disclosure adopts the design of a fixing seat, which places the fixing seat in a slot for placing water cup, and fixes the holder through the slot for placing water cup, which greatly facilitates the fixing of the holder. At the same time, this solution also designs a size adjusting sleeve to adjust the size, the design of the sleeve makes the holder suitable for different models, moreover, the product can be rotated 360 degrees around the slot, which greatly facilitates the use of the user.