Based on the analysis of fluid potential, chemical analysis of oil field water, study of the content and ratio of nitrogen-bearing compounds in crude oil, and the temperature of fluid inclusions, the authors suggest that Hercynian oil and gas in the Tazhong area should come mainly from the northeast and northwest and formed the Tazhong-4 oil accumulation. Through an analysis of the migration direction of fluid, the authors consider that Tazhong-4 oil accumulation was destroyed by washing of fresh water during the Himalayan period, thus resulting in great decrease of the reserves of oil and gas. In the Lunnan area, oil and gas came mainly from the Manjia'er depression in the southern part of the Lunnan area as well as the Halahatang and Caohu depressions at both sides of the Lunnan area, of which the Caohu depression has supplied gas twice and the other two depressions have supplied gas three times. The study of the migration direction of fluid is helpful to gaining knowledge of the distribution characteristics of oil and gas and has great significance for the determination of favorable zones and targets of petroleum exploration.