North Dagang Wetland Nature Reserve is situated in the southeast of Tianjin, China. It is the biggest wetland nature reserve in Tianjin. An investigation into the diversity of the moth community was carried out from June 12 to October 14, 2001, and then from April 12 to October 30, 2002. The investigation was conducted in order to identify the moth species in wetlands, study their dynamic laws, select indicator insects to indicate wetland quality, and assist in the study and protection of wetlands. A total of 132 moth species were collected, which belonged to 105 genera in 17 families. The data about insects which was collected during the survey was listed and constructed in terms of species-abundance, indices of diversity (H′), evenness (J′), specific richness (S) and individual number (N) using the Microsoft Excel Program. The status of the wetlands was also analyzed using the moth community species-abundance curve, indices of diversity, the connection between evenness and richness indices, etc. The results show that moth species in the wetlands were not rich, and the moth community was unstable. In other words, the living environment of the moths and the environmental quality of the wetlands were unstable due to the serious degeneration of the wetland environment and human activities.