This book discusses systematically the theoretic approach to extension engineering methods and their applications.Its major content includes:Chapter One:the fundamental idesa,theories and approaches.Chapter Two:the extensibility and extension method of matter-element.Chapter Three:evaluation methods and lozenge (rhombus)mode thinking.Chapter Four:transformation methods of matter-elements.Chapter Five:extension engineering methods.This book is designed for college teachers and students,engineers,technicians as well as management personnel concerned.