Now there are more than 1000 welding machine manufacturer in China, whose munufacturer is the most, and whose output of welding machine is largest in the world. But most o Chinese munufacturers have not their own technology. They have to copy other manufacurer’s technology and compete under low price and low profit. At present, there are four kinds of mainstream technology: 1. MOS transistor(electron tube) inverting welding machine,represented by RUILIN, JIASHI, .its cost is very low, and the capacity is very small. So it is fit for the manual welding,argon arc welding, under small current for civilian use. Many small plants can copy and imitate. 2. Soft switching inverting welding machine, represented by AOTAI, whose inverting frequency is 20KHz, it is imitated by many small plant. 3. SCR (silicon controlled rectifier) welder, represented by PANASONIC. It took up a large part of market. There are many postiches too. But as the inverting and digital technology progresses, the SCR market become small and small. 4. All digital welding machine, represented by TAIYUAN NEBULA, it develops faster, and come to be the extend for the future.