This century has seen research on Lao-zi on Mainland China divided into three areas; historical research, philosophical research and cultural research. These three areas have proceeded through three phases or, it could be said, have reached three pinnacles. The first phase was during the 1920's and 1930's, where different understandings of the literary records of Lao-zi during pre-Qin China were debated. This included discussions on Lao-zi the man and Lao-zi the book and their historical positioning. (That is whether they appeared during the Spring-Autumn Period or the War-ring States Period.) The second phase was during the 1950's and 1960's where debates on Laozi's concept of ”Dao” and other import- ant categories took place. Heated discussions were held as to whether Lao-zi's philosophy was primarily materialism or idealism.In the past ten years a new phase in the research on Lao-zi has taken place. Changes have taken place in understanding theoretical aspects and the background of certain Concepts in Lao-zi's philosophy. This in turn has scholars diligently searching for a meaning for Lao-zi's philosophy in the modern world.