The mismatch between system training and operating conditions can seriously deteriorate the performance of ASR systems. The maximum a posteriori (MAP) estimation is used for the adaptation of HMM-based multivariate Gaussian mixture models (GMMs). In this paper, we propose an environment independent ASR model parameter adaptation approach based on Bayesian parametric representation (BPR). Compared to the MAP method, the BPR adaptation method has better performance with limited adaptation data. The performances of the two methods are investigated in the experiments designed on the AURORA 2 noisy speech database.