We introduce the notion of a crystal base of a finite dimensional qdeformed Kac module over the quantum superalgebra Uq(gl(m|n)), and prove its existence and uniqueness. In particular, we obtain the crystal base of a finite dimensional irreducible Uq(gl(m|n))-module with typical highest weight. We also show that the crystal base of a q-deformed Kac module is compatible with that of its irreducible quotient V (λ) given by Benkart, Kang and Kashiwara when V (λ) is an irreducible polynomial representation.where P(Φ − 1 ) is the power set of the set of negative odd roots of gl(m|n) and B m,n (λ) is the crystal of V m,n (λ). Also, the crystal structure on (1.1) can be described easily (Section 5.1).We next show that the crystal base of K(λ) is compatible with that of its irreducible quotient V (λ) when V (λ) is an irreducible polynomial representation (Theorem 4.11), that is, the canonical projection from K(λ) to V (λ) sends the crystal base of K(λ) onto that of V (λ). Hence we may regard the crystal of V (λ) as a subgraph of the crystal of K(λ). We give a combinatorial description of its embedding (Section 5.3) using the (m|n)-hook tableaux crystal model for V (λ) and the skew dual RSK algorithm introduced by Sagan and Stanley [16].The paper is organized as follows. In Section 2, we give necessary background on the quantum superalgebra U q (gl(m|n)). In Section 3, we review the crystal base theory developed in [1]. In Section 4, we define the notion of a crystal base of a Kac module and state the main results, whose proofs are given in the following two sections.Acknowledgement Part of this work was done while the author was visiting the Institute of Mathematics in Academia Sinica, Taiwan on January 2012. He would like to thank S.-J. Cheng for the invitation and helpful discussion, and the staffs for their warm hospitality.2. Quantum superalgebra U q (gl(m|n)) 2.1. Lie superalgebra gl(m|n). For non-negative integers m, n, let [m|n] be a Z 2graded set with [m|n] 0 = { m, . . . , 1 }, [m|n] 1 = { 1, . . . , n } and a linear ordering m < . . . < 1 < 1 < . . . < n. We denote by |a| the degree of a ∈ [m|n]. Let C [m|n] be the complex superspace with a basis { v a | a ∈ [m|n] }, where the parity of v a is |a|.Let gl(m|n) denote the Lie superalgebra of [m|n] × [m|n] complex matrices, which is spanned by E ab (a, b ∈ [m|n]) with 1 in the ath row and the bth column, and 0 elsewhere [8].Let P ∨ = a∈[m|n] ZE aa be the dual weight lattice and h = C ⊗ Z P ∨ the Cartan subalgebra of gl(m|n). Define ǫ a ∈ h * by E bb , ǫ a = δ ab for a, b ∈ [m|n], where ·, · denotes the natural pairing on h × h * . Let P = a∈[m|n] Zǫ a be the weight lattice of gl(m|n). For λ = a∈[m|n] λ a ǫ a ∈ P , the parity of λ is defined to be λ 1 + · · · + λ n mod 2 and denoted by |λ|. Let ( · | · ) denote a symmetric bilinear form on h * = C ⊗ Z P given by (ǫ a | ǫ b ) = (−1) |a| δ ab for a, b ∈ [m|n].Let I = I m|n = { m − 1, . . . , 1, 0, 1 . . . , n − 1 }, where we assume that I m|0 = { m − 1, . . . , 1 } and I 0|n = { 1 . . . , n−1 }. Then with respect to ...