As　the　first　practical　fountain　code,　LT　code　is　still　important　as　a　component　of　the　Raptor　code　and　used　in　various　applications.　Usually,　robust　Soliton　distribution　(RSD)　is　used　as　the　degree　distribution　for　LT　code.　The　robustness　of　RSD　is　based　on　the　parameters,　c　and　δ,　which　can　be　adjusted　to　obtain　better　performance　of　LT　codes　with　different　length.　In　this　paper,　we　anaylze　the　impact　of　the　distribution　parameters　on　the　mean　degree　and　investigate　the　impact　on　the　decoding　performance　of　LT　code　through　simulation.　©　2012　IEEE.