Forest carbon sink is an approach to realize the compensation of forest ecological values, originated from Kyoto Protocol Forest carbon sink can promote economic sustainable development and help developed countries implement their GHGs emission reduction But it may influence the local ecological environment without proper legal regulation, especially does harm to biodiversity conservation It is necessary for states to make law regulating forest carbon sink and protecting biodiversity How to make a balance between forest carbon sink and biodiversity conservation is an urgent issue in environmental law Through three legislative stages in beforehand control, processing control and post-action remedy, we can regulate forest carbon sinks trading and protect biodiversity In the first stage, environmental impact assessment mechanism examines whether forest carbon sinks trading does harm to biodiversity conservation In the second stage, legislation supervises the dynamic effects of forest carbon sinks on biodiversity In the third stage, punishment mechanism on destroying biodiversity is supposed to be established