High density polyethylene (HDPE)/ethylene-vinyl acetate copolymer (EVA) blends with selective crosslinking the EVA phase were prepared and the crystallization, rheological, and mechanical behaviors were studied. Selective crosslinking of EVA component could greatly improve both tensile and impact strengths of the HDPE-rich blends and influence melting enthalpy at different annealing temperature in successive self-nucleation and annealing procedure. Dynamic mechanical analysis reveals that glass transition temperatures of both the HDPE and EVA components are lowered upon blending and are raised upon crosslinking. The uncrosslinked HDPE/EVA blends are unstable in the melt and show increment in storage modulus (G) and decay in loss tangent (tan) with annealing time associated with phase coarsening. However, morphology of selectively crosslinked blends in the melt state is highly unstable, characterized by a fast migration of uncrosslinked HDPE component out of the crosslinked EVA phase to the surface resulting in a rapid decay in G and an increment in tan at the early stage of annealing. POLYM. ENG. SCI., 54:2848-2858, 2014. (c) 2014 Society of Plastics Engineers