The invention is suitable to the technical field of medical apparatuses and discloses a ultrasonic diagnosis mechanical arm and a ultrasonic diagnosis system. The mechanical arm comprises a rack capable of being held by a user, a position micro-adjusting mechanism connected to the rack and adjusting two-degree of freedom of a plane where the rack lies, a gesture adjusting mechanism connected under the position micro-adjusting mechanism and adjusting three-degree of freedom of a ultrasonic probe gesture, and a depth feeding mechanism connected to the gesture adjusting mechanism, as well as a mechanical arm tail end connected to the gesture adjusting mechanism and connected with the ultrasonic probe. A horizontal position of the ultrasonic probe can be micro-adjusted via the two-degree of freedom position micro-adjusting mechanism; the ultrasonic probe gestures and depths can be adjusted via the three-degree of freedom gesture adjusting mechanism and the depth feeding mechanism; and a surface body position of a patient can be well positioned, so the patient can be well diagnosed by a doctor.