Poly methyl methacrylate (PMMA), widely used as a prosthodontic denture base, the denture base materials should exhibit good mechanical properties and dimensional stability in moist environment. In the present research, efforts are made to develop the properties of PMMA resin that used for upper and lower prosthesis complete denture, by addition four different types of nanoparticles, which are fly ash, fly dust, zirconia and aluminum that added with different ratios of volume fractions of (1%, 2% and 3%) to poly methyl methacrylate (PMMA), cold cured resin (castavaria) is the new fluid resin (pour type) as a matrix. In this work, the Nano composite and hybrid Nano composite for prosthetic dentures specimens, preparation was done by using (Hand Lay-Up) method as six groups which includes: the first three groups consists of PMMA resin reinforced by fly ash , fly dust and ZrO2 nanoparticles respectively, the second three groups consists of three types of hybrid Nano composites, which includes ((PMMA: X% nF.A)+ (1%Al + 3% ZrO2)), ((PMMA: X% nD.A)+ (1%Al + 3% ZrO2)) and ((PMMA - X%nZrO2)+(1%F.A + 3%F.D)) respectively. The hardness and flexural tests results show that the values of the hardness, flexural strength, Maximum shear stress and flexural modules increased and with the addition of Nano powders (fly ash, fly dust, zirconia, and aluminum). And the results showed that the maximum values of hardness reach to (84.166) for ((PMMA: 3%nZrO2) + (1%F.A + 3%F.D)) hybrid Nano composite, whereas the maximum values of hardness for Nano composite reach to (83.333) for (PMMA: 3%nZrO2) Nano composite. Also, the results showed that the maximum values of flexural strength and Maximum shear stress reaches to (101MPa) and (2.4738MPa) respectively for (PMMA: 2%nF.D) Nano composite. Moreover, the results showed that the maximum values of flexural modules reaches to (13.95GPa) for ((PMMA: 3% nF.A) + (1%Al + 3%ZrO2)) hybrid Nano composite, whereas the maximum values of flexural modules for Nano composite reach to (12GPa) for (PMMA-3%nZrO2) Nano composite.