The molding condition and mechanical properties of the unidirectional UHMW-PE fiber reinforced linear lowdensity polyethylene (LLD-PE) composites were investigated. The most important fabrication parameter of thermoplastic materials used for such a composite was molding temperature. First differential scanning calorimetry (DSC) (thermal analysis) was performed and the melting point for UHMW-PE fiber and PE matrix film was measured. Mechanical properties of UHMW-PE fiber by high heat treatment were investigated. Then, simulate DSC measurements were performed for specimens subjected to several types of thermal history. Time-temperature profile in simulate DSC measurements referred to the actual processing conditions. The effects of molding temperature on mechanical properties were investigated. At the molding temperature observed re-fusion peak of UHMWPE fiber in DSC measurements, mechanical properties in longitudinal direction was maintained. On the other hand, mechanical properties in transverse direction were highest value. From these results comparing with the theoretical value by Law of mixture, it is considered that interfacial properties of PE/PE composites were changed by the molding temperature. PE/PE composites with optimum molding condition could be fabricated by using the suitable molding temperature between PE fiber and matrix.