Disclosed is a three dimensional mechanical ultrasound probe, which includes a transducer, a driving motor and a transmission mechanism configured to drive the transducer to reciprocatingly oscillate within a predetermined angle. The transmission mechanism includes a transducer base fixed and connected with the transducer, a face gear arranged on the transducer base, and a cylindrical gear meshed with the face gear. A rotating shaft of the face gear is positioned on the transducer base, and the face gear drives the transducer base to reciprocatingly oscillate. A transmission shaft is arranged on the axis of the cylindrical gear, and the transmission shaft is connected with the driving motor. The three dimensional mechanical ultrasound probe provided by the present application aims at simplifying the internal structure of the three dimensional mechanical ultrasound probe, reducing the internal installation complexity and improving motion stability.