A screw mechanism for adjusting an angle of an antenna module is disclosed in the present invention. The screw mechanism includes a screw rod. The screw rod includes a rod portion. A thread is formed on a first area of the rod portion. An annular protrusion is formed on a second area of the rod portion, and an outer diameter of the annular protrusion is greater than an outer diameter of the rod portion. The screw rod further includes a handle disposed on an end of the rod portion adjacent to the second area. The screw mechanism further includes an accommodating component whereon a sunken part is formed. The sunken part is for accommodating the annular protrusion of the screw rod. The screw mechanism further includes a screw having a side hole. The screw is installed on the first area of the screw rod and moves along the thread.