The invention discloses a moving method and system for a mechanical arm. The method includes the steps that a part grasping part of the mechanical arm moves to a fetching point, and meanwhile fetching enabling signals are detected; if no fetching enabling signal is detected in the moving process, the part grasping part is controlled to stop at a first preset holding point; after the mechanical arm receives the fetching enabling signals, the part grasping part is controlled to move to the fetching point from the first holding point; the part grasping part of the mechanical arm moves to a discharging point, and meanwhile discharging enabling signals are detected; if no discharging enabling signal is detected in the moving process, the part grasping part is controlled to stop at a second preset holding point; after the mechanical arm receives the discharging enabling signals, the part grasping part is controlled to move to the discharging point from the second holding point; after discharging is completed, the mechanical arm continues to execute the step that the part grasping part of the mechanical arm is moved to the fetching point. The mechanical arm conducts detection while moving, the flexibility of control over the mechanical arm is improved, time can be effectively saved, and production efficiency is improved.