The Great Barrier Reef is internationally recognised for its natural and heritage value. Australian Government established the Great Barrier Reef Marine Park under the Great Barrier Reef Marine Park Act, 1975. The Act provides a legal regime for the protection of the natural and heritage values of the Reef. The Act incorporated spatial zoning and Marine Spatial Planning (MSP) to achieve the objective of ecologically sustainable use and management. The Act applies many principles including Ecosystem-Based Management (EBM) to achieve the objective. The current management mechanism under MSP has a significant achievement in the protection of the Reef region. However, there are many shortcomings of the Act to achieve the objective of ecologically sustainable use and management. Protection of ecosystem health, resilience, marine pollution and risk of climate change are the challenges that the Park faces. This paper analyses the shortcomings and achievements of the Act based on the Review Report, 2006, the Outlook Report 2009 and the Outlook Report 2014. The analysis explores that the overall performance of the Act is poor. Therefore, this research recommends for new management practice under a strategic action plan. The Plan should provide adequate protection against the new challenges that the Park faces.