Fiber reinforced composites are considered to replace metallic components in various industries because of light weight, high specific strength, stiffness and higher corrosion resistance etc. It is well-known that the mechanical properties of the composites depend on the properties of fiber and matrix, and the interface between them. Among all fiber reinforced composites, carbon fiber (CF) reinforced polymers exhibit remarkable properties. Compared to other thermosetting resins such as epoxies, polyesters and vinyl esters, polyimides (PIs) have outstanding mechanical properties, high thermal stability and good chemical resistance. Therefore, the high performance PI based CF composite materials have much attention for the application in the industrial fields. Herein, a series of molecular weight (MW)-controlled aromatic PI was successfully synthesized via the polycondensation and MWs of them were determined by GPC. CF reinforced composites with aromatic PIs were fabricated by hot-press molding or resin infusion molding. To investigate the effect of MWs, the mechanical properties and morphological features were measured by dynamic mechanical thermal analysis (DMA), thermogravimetric analysis (TGA), tensile measurement, and scanning electron microscope (SEM).