This study presents a new process to fabricate gapless triangular micro-lens array (GTMA). The process includes optical simulation with tracepro, UV lithography, photoresist reflow process, Ni electroplating and hot embossing technique. After photoresist triangular column array is defined using UV lithography, reflow process is applied to melt photoresist triangular column array into the shape of triangular micro-lens array. With this reflowed triangular micro-lens array, Ni is deposited and covered uniformly on the triangular micro-lens array using electroplating. The growth rate of Ni is controlled at electroplating current density of 1 Ampere Square Decimeter (ASD; A/dm2). After this electroplating process is finished, a mold of GTMA is obtained, which is served as primary mold. Subsequently, with passivation technique applied on this mold¡¦s surface, electroplating process is applied again to obtain a secondary mold. Next, this secondary mold is served as master for the subsequent hot embossing process to replicate the GTMA pattern onto polymeric material PMMA and PET sheet. The mold with stiffness and hardness plays an important role in GTMA hot embossing process. In addition, this GTMA used as optical film can offer a 100 % fill factor and a simulation of optical coupling efficiency of 66.7% to improve luminance of backlight module (BLM). In addition, this study presents the fabricated molds of GTMA with different aspect-ratio about 0.109 and 0.133. The optical measurement of BLM shows that this optical film of GTMA pattern with aspect-ratio about 0.109 can increase 15.1% of luminance and with aspect-ratio about 0.133 can increase 22.1% of luminance.