Being the heat source of arc spray, the characteristics of arc are of importance for properties of coatings. In this paper, the arc shape in the wire arc spray process was analyzed in the aid of high-speed digital camera. It is testified that the arc has the elliptical shape. This type of shape is favorable for heating the metal particles. The arc isn’t always in burning state and it is extinguished frequently. There are two kinds of reasons for arc extinguish. The first one is that the two metal wires short circuit. The second one is that the imperfect melted metal stretches the arc long, and then this part melted and broken away from the metal wires’ tips. If we can control the metal wires state, the properties of coatings will be improved.