In recent years, research is underway worldwide by scientists to successfully replace the majority of structural components that are denser, high weight and are costly with fiber reinforced polymer (FRP) composites materials that are lightweight and low cost without sacrificing strength requirements in various applications. Among the available composite fabrications techniques, Resin infusion process is a competent and most effective technique which has been successfully used by the industries for production of complex FRP composite components and structures with intricate geometric details. However in any fabrication process, understanding the effect of critical process parameters is highly important to ensure high quality of final composite materials with superior mechanical properties. Therefore, the present study is focused on studying the effect of critical process parameters such as fiber architectures, number of layers and inlet vacuum in the mould on the quality and mechanical properties of the e-glass/polyester composite laminates fabricated by means of resin infusion technique. Three different fiber architectures: (i) Chop strand (ii) Woven mat and (ii) unidirectional mat are selected. Moreover, three different fiber reinforcements layers (as 4 layers, 5 layers and 6 layers) with varied vacuum pressures: (i) 200 mm of Hg, (ii) 300 mm of Hg, and (iii) 400 mm of Hg are selected in the present study for preparation of samples. The results indicated a considerable effect of inlet pressure and the fiber architecture on the materials performance.