A novel copper and steel composite pipe, a manufacturing method, application and a welded structure body is described herein. The novel copper and steel composite pipe includes a copper pipe and a steel pipe. The steel pipe includes a first end, a second end and a middle part. The copper pipe includes a first end and a second end. The length of the copper pipe is less than that of the steel pipe. The copper pipe and the steel pipe are sleeved. The distance from an end surface of the first end of the copper pipe to an end surface of the first end of the steel pipe is less than 10 mm. The second end of the copper pipe is positioned at the middle part of the steel pipe, and the copper pipe and the steel pipe are welded and connected in a way of melting base materials.
