For the first time , we present a Bayesian time-resolved spectral study of the X-ray afterglow datasets of GW170817/GRB17017A observed by the Chandra X-ray Observatory . These include all 12 public datasets , from the earliest observation taken at t \sim 9 d to the newest observation at \sim 359 d post-merger . While our results are consistent with the other works using Cash statistic within uncertainty , the Bayesian analysis we performed in this work have yielded Gaussian-like parameter distributions . We also obtained the parameter uncertainties directly from their posterior probability distributions . We are able to confirm that the power-law photon index has remained constant of \Gamma \sim 1.6 throughout the entire year-long observing period , except for the first dataset observed at t = 8.9 d when \Gamma = 1.04 \pm 0.44 is marginally harder . We also found that the unabsorbed X-ray flux peaked at t \sim 155 d , temporally consistent with the X-ray flare model suggested recently by Piro et al ( 2018 ) . The X-ray flux has been fading since \sim 160 days after the merger and has returned to the level as first discovered after one year . Our result shows that the X-ray spectrum of GW170817/GRB170817A is well-described by a simple power-law originated from non-thermal slow-cooling synchrotron radiation .