【Abstract】 Objective To establish the monitoring system and network of the vector and know the flies density dynamics and its population distribution in the early reconstruction after earthquake in Shifang city. Methods The fly density and its population composition were monitored in tents, removable house, trash can, toilet and hospitals by cage trapping method in 5 towns in Shifang city. Results The flies caught mainly belonged to 3 species，6 genera. Of which,  Chrysomya megacephala was the dominant specie, accounting for 56.0% of the total. In monitored 5 township (town), the density of fly was higher in Luoshui town and Yinghua town, with the density of 358.0 individuals/cage and 91.7 individuals/cage , and the density of flies in Mazu town was the lowest with the density of 13.0 individuals/cage. Conclusion This investigation primarily knew the flies density and its population composition after earthquake in Shifang and filled a gaps in this area, which could provided the basis for the prevention and control of flies.