Nonisothermal crystallization kinetics of the blends of three ethylene-butene copolymers with LDPE was studied using differential scanning calorimetry (DSC) and kinetic parameters such as the Avrami exponent and the kinetic crystallization rate (Z(c)) were determined. It was found that the pure components and the blends have similar Avrami exponents, indicating the same crystallization mechanism. However, the crystallization rate of the blends was greatly influenced by LDPE. The Z(c) of all the blends first increases with increasing LDPE content in the blends and reaches its maximum, then descends as the LDPE content further increases. The crystallization rate also depends on the short-chain branching distribution (SCBD) of the ethylene-butene copolymers. The Z(c) of the pure component with a broad SCBD is smaller, but its blends have a larger crystallization rate due to losing highly branched fractions after blending with LDPE.