Covered electrode diameter: determined according to plate thickness, number of welding layers and joint form. Welding current: According to covered electrode diameter, plate thickness, construction location and covered electrode type, too small is easy to clamp the unfused arc, and too large is easy to cause undercut and burn-through. Welding speed: according to the current, if it is too fast, the weld will become narrow, uneven and undercut; If it is too slow, the weld will become wider, the weld will become higher and the heat affected zone will become larger. Power polarity: determined according to covered electrode type. Number of welding layers: according to the groove size and welding angle. Dimensional heat input: the heat input of welding arc heat to unit length weld is mainly aimed at some materials such as low alloy steel and stainless steel. If the heat input of this plate is too large, the joint performance will be reduced or even cracked. In fact, welding current and welding speed directly affect the heat input. Preheating temperature: Some materials with high hardness and poor weldability need to be preheated to avoid cracks, such as cast iron. Heat treatment: Another method is called post-heating, which is different from the two methods. Post-heating is a heat treatment immediately after welding or heat preservation and slow cooling, so as to avoid the formation of hard and brittle phenomena and reduce the occurrence of cracks. In the process of heat treatment, heat treatment is carried out to improve the performance of the joint or eliminate stress.