Recently, the first nitrogen-containing iron pnictide superconductors ThFeAsN, has been discovered with Tc = 30 K. We have investigated the gap symmetry in ThFeAsN using musr. Interestingly by tuning the oxygen doping levels in ThFeAsN1-xOx, two superconducting (SC) domes are found, one for x=0-0.15 with Tc below 30 K and the second one fpr x=0.2=0.6 with maximum Tc = 15 K. In iron pnictides, superconductivity always emerges beside the stripe type AFM order, forming an asymmetry dome with maximum Tc near the critical point of AFM region. Spin fluctuations may mediate the electron pairings and establish the correlations and condensations, representing as an order-parameter-like spin resonance cantering around certain energy (ER) which is linearly scaling with Tc . Here we proposed to investigate the spin resonance and also high energy spin fluctuations in ThFeAsN1-xOx using MERLIN.