With the elaborate division to microfacieses, It reveals that different sedimentary microfacies of sand body has obvious difference in some sectors, such as stratigraphy, reservoir physical properties, sedimentary structure and heterogeneity characteristics. Ma 19 well of Dongying formation in Xinglongtai oil field is typical fluvial to swamp facies, it contains many microfacieses, makes reservoir construction very complicated. With the study on microfacieses, it knows that distribution of reservoir sand bodies and accumulation of hydrocarbon, determines the regularity of residual distribution, thereby, adopt effective measures to potential tapped, lay the foundation for further exploitation of old filed and enhanced ultimate recovery