This book is guided by the teaching syllabus of the Ministry of Education and the professional standards, and it also consider the actual situation of the gas welding and electrical welding as well as the situation of the students of secondary professional schools. It is organized in the form of project teaching and it emphasizes on the task drive in. It projects the basic knowledge and skills needed for the primary and middle-level gas and electrical welders. This book emphasizes on the practicality and has plenty of images and text, so as to make the readers understand as soon as possible. This book can be used as the textbook for the major of electro mechanics in the secondary professional schools, and for the training classes for the primary and middle-level workers for gas welding and electrical welding.