In hard-to-predict large scale natural disasters such as Hurricane 'Katrina', government alone cannot cope with problems successfully simply because resources and capabilities of governments are inadequate to meet the demand. Therefore, government needs to pay attention to collaborative network of autonomous actors with diverse resources and capabilities from both public and private sectors. Especially, government needs to play a pivotal role of designing and managing these collaborative networks.From the case of Hurricane Katrina, we conclude both U. S. federal and state governments still relied on traditional hierarchical governance in disaster management, and consequently they failed in disaster management due to the lack of collaborative networks. This implies that governments's role of designing and managing collaborative network is critical in disaster management.