It is an effective approach to le the influence of environmental parameters,such as additive noise and channel distortions, from training data for robust speech recognition.Most of the previous methods are based on maximum likelihood estimation criterion. However,these methods do not lead to a minimum error rate result. In this paper, a novel discrimina-tive leing method of environmental parameters, which is based on Minimum ClassificationError (MCE) criterion, is proposed. In the method, a simple classifier and the Generalized Probabilistic Descent (GPD) algorithm are adopted to iteratively le the environmental parameters. Consequently, the clean speech features are estimated from the noisy speech features with the estimated environmental parameters, and then the estimations of clean speech features are utilized in the back-end HMM classifier. Experiments show that the best error rate reduction of 32.1% is obtained, tested on a task of 18 isolated confusion Korean words, relative to a conventional HMM system.