The construction of normalized biholomorphic convex mappings in the Reinhardt domain Dp{(z1,z2,....zn):z1 p1+z1 p2+....+zn pn 2,j=1,2,.....n,) of n is discussed.The authors set up a Decomposition Theorem for such mappings. As a special case, it is proved that, for each suchthis derives the Decomposition Theorem of normalized biholo morphic convex mappings in the polydisc whichwas gotten by T.J. Suffridge in 1970.