Currently, there are many varieties of slotted casing used for limited sand control in the world, and there are no "API" or national or industry standards. Most of them adopt the production and inspection standards set by the company. For many years, many experts at home and abroad have been studying how to process and manufacture a slotted casing that is used for oil well and gas well completion, gravel filling and sand control, and to form certain oil well production strings. Because there are many manufacturing methods, it is easy to cause confusion in the market. It is understood that cutting, milling, drilling, beam and inlay methods are the most typical and most common methods. Each has its own application scope and field, the processing and production quality is different, and the drilling method is different. So far, an effective method has not been found to process and manufacture a slotted casing that is suitable for oil extraction and sand prevention, has a seam that can withstand high external forces, is not easily deformed and blocked, and has practical value.