Infrared radiative parameters under high temperature was calculated using RJMCMC method under Bayesian framework presumed Smeared Rotational Band model (SRB), in order to solve the problem of radiation calculation for high speed vehicle infrared signature research. The process of calculation does not need any database of parameter or priors about transition. The experiment from simulation and measured data demonstrates that the position of vibrational transition have been estimated precisely. Simultaneously, the change law of parameter estimation was consistent with theoretic SRB model, from which the integration of radiative parameters under different temperature approximated the line by line calculation (LBL) result very well.