Lean Production, which was born in manufacturing industry, is considered to be the most suitable production mode for the modern manufacturing enterprises. This paper investigates the application of Lean Production Thinking in the assembly technology, and proposes the concept of Lean Assembly. The Lean Assembly could be described as follows: Eliminating all wastes in assembly process through certain management tools and technologies. There are three sub goals of Lean Assembly: zero inventories, high flexibility, zero defects. What’s more, this paper studies several key technologies, such as assembly line balancing, mixed-model scheduling, part supplying, assembly cell, virtual assembly etc.