Though South China Sea has become the hottest spot of Northeast Asia, researches about the claims of Malaysia and Brunei are not enough. This paper focused on the claim of Malaysia and Brunei in South China Sea issue, especially on the ambiguous part. Clearly Malaysia claims several features of Spratly islands, but it is not confirmed whether Malaysia also claims islands besides which it occupied. And the Malaysia's claim about baseline and territorial sea also have an ambiguity, especially in North Borneo erea. Brunei's claim on South China Sea is just a maritime right claim, as it hasn't claimed Louisa Reef as its territory officially. Brunei's maritime claim is all measured from the mainland and basically in accordance with UNCLOS. Recently both Malaysia and Brunei consider features of Spratly islands generating no right of EEZ nor continental shelf, while that could be disputable from other claimants' perspective.