The polyacrylonitrile (PAN)-based and pitch-based carbon fiber-reinforced nanoparticle filled polyimide based multiscale hybrid composites have been fabricated using vacuum assisted resin transfer molding (VaRTM) and autoclave curing. The carbon fibers used in this study were high tensile strength PAN-based (T1000GB) and high modulus pitch-based (K13D) carbon fibers. Fiber orientations of the T1000GB/K13D hybrid composites were set to [0(T1000GB)/0(K13D)]2S (T1000GB and K13D unidirectional layers were alternately and symmetrically laminated). The fiber volume fraction was 50 vol% (T1000GB: 24.9 vol%, K13D: 25.1 vol%). Polyimide used in this study was a commercially available polyimide precursor solution (Skybond 703). Four different types of nanoparticle (25nm-C, 20-30nm-β-SiC, 130nm-β-SiC and 80nm-SiO2) and particle volume fraction was 5.0 vol% used for the inclusion. The tensile properties and fracture behavior of T1000GB/K13D nanoparticle filled and unfilled hybrid composites have been investigated. For 25nm-C, 20-30nm-β-SiC and 80nm-SiO2 nanoparticle filled and unfilled hybrid composites, the tensile stress-strain curves show a complicated shape. By the high modulus pitch-based carbon fiber, the hybrid composites show the high modulus in the initial stage of loading. Subsequently, when the high modulus carbon fiber begin to fail, the high strength fiber would hold the load (strength) and the material continues to endure high load without instantaneous failure.