Films made of metallocene catalyzed polyethylene (mPE), low-density polyethylene (LDPE), and their blend were prepared to investigate how LDPE influences the hot tack of film. Experimental results showed hot tack is independent of film thickness. The addition of 30 wt % of LDPE can increase the hot tack of mPE film. The thermograms of differential scanning calorimetry (DSC) suggest the respective partial melting and recrystallization of those smaller size crystals at the bond forming and joint fracture stages play very important roles. The large amount of partial melting and high flow may induce a higher degree of molecular diffusion. Higher residual crystallinity and recrystallization at the hot tack testing process may induce higher resistant to bond fracture. Those two positive influences show that the mPE/LDPE him has the higher hot tack. The evidence from optical (higher optical transmission and lower haze) as well as viscoelastic (higher storage modulus and lower melt viscosity) properties further support this hypothesis.