Based on the UNCLOS, the obligations and responsibilities and the nature and constituent elements of liability of sponsoring states are clearly defined in the international law. However, as the criteria of “due diligence” and the scope of sponsoring state liability etc. are still not clear, and the exploration and exploitation in the Area is highly risky, sponsoring states are faced with high risk of liability. In order to effectively avoid the liability of environmental damage, sponsoring states should improve their domestic deep seabed legal system to fulfill their environmental obligations in the Area, and it is necessary to impose a high threshold through counter guarantee system as a form of security. In addition, the liability burden can be channeled to the contractor or insurer. Limits on liability can reduce the uncertainty of sponsoring state liability so as to alleviate the liability risk of deep seabed activities.