Environmental data with an appropriate type and quality is the key factor for the successful implementation of environmental decision and technology. However, it is lack of criteria, practices and standards for the collection and management of environmental data in Taiwan. Therefore, the data quality of environmental data is difficult to be evaluated for its intended use. Therefore, the main aim of this project is to develop an Environmental Data Quality System (EDQS). The EDQS is the critical point for ensuring that environmental programs and decisions are supported by data of the type and quality needed and expected for their intended use. Therefore, the decisions involving environmental technology are supported by appropriate quality-assured engineering standards and practices. The major works of this project including: (1) to propose the policy of environmental data quality for Taiwan EPA, to develop the criteria and standard for data quality classification, and development the data Quality Management Plan (QMP); (2) to develop the criteria and standard for Data Quality Objectives (DQOs); (3) to revise the criteria and standard for Quality Assurance Project Plan (QAPP); (4) to develop the criteria and standard for preparation of Standard Operating Procedures (SOPs); (5) to propose the system analysis of computer-aid management system for the EDQS.