Background: Radiation-sensitive polymer gels are among the most promising three-dimensional dose verification tools and tissue-like developed to date. Among the special features of this type of dosimeters, is be doped with other elements or chemicals which made them appropriate for investigating of dose enhancement with contrast agents, by high atomic number. Material and Methods: In this study, To evaluate dose characteristic of the normoxic polymer gel (MAGICA) such as dose response , dose sensitivity and dose resolution And To find the gold nanoparticles (50 nm) effects of the normoxic polymer gel such as a DEF in mega voltage radiation therapy (18 MV-X ray). Also it is compared by method of Monte Carlo simulation with MCNPX Code. Results: The results shown that the MAGICA polymer gel dose response in dose range of 0 to 600 cGy is linear and dose resolution in this range, is less than 0.7 Gy. MAGICA Polymer gel dosimeter response R2 was increased by added gold nanoparticles. Absorbed dose enhancement factor by adding of gold nanoparticles with the 0.1, 0.2, 0.4 mM concentrations was 10%, 2% and 4% respectively. Conclusion: In this study, Shielding effect or self absorption happened on 0.2 mM & 0.4 mM. And optimum gold nanopartiles concentration to achieved maximum absorbed doe is 0.1mM, so that is useable for clinical studies.