Abstract: The opinions of academic field on 'Laozi' is not animous. Some think that 'Laozi' would be a philosophical book, Some regard it as a book helping emperor, The others consider it a book on the art of war. All above points have many evidences and reasons supporting. However, I think that there are only two words, which are Tao' and 'dharma' frequently appearing in 'Laozi'. 'Tao' is taproot and 'dharma' is the use of 'Tao'. The rule of 'Tao' is spontaneity and wuwei (do nothing and let things take their own course), so Lao-zi went after spontaneity and wuwei.