In the current research, sensitivity analysis of the accelerator and fissionable and non-fissionable spallation targets containing U-238, Pb, LBE and W materials, Y n/p (spallation neutron yield), E p (proton energy), G (energy gain), ϕ* (importance of neutron source), K eff (effective multiplication coefficient), K s (source multiplication coefficient) and I p (accelerator current) for two cases of K s including: 0.91 and 0.97 in an Accelerator Driven Subcritical Reactor TRIGA (TRIGA-ADSR) were studied. These neutronic factors were computed by MCNPX code. The obtained results of this study show that for the Y n/p and G parameters, there is an optimum energy from 800 to 1000 MeV. Furthermore, according to the results, if this reactor would be operated close to criticality, the effect of reactivity insertion on the core power is raised. Also, the optimum value of K s = 0.97 was chosen as adequate multiplication coefficient in this research because of appropriate margins. Lastly, the results of these investigations show that analysis of sensitivity and specificity of the accelerator and spallation target factors is required to optimize the neutronic plan of ADSR.