A speech recognition system for a mobile terminal includes an acoustic variation channel unit and a pronunciation channel unit. The acoustic variation channel unit transforms a speech signal into feature parameters and Viterbi-decodes the speech signal to produce a varied phoneme sequence by using the feature parameters and predetermined models. Further, the pronunciation variation channel unit Viterbi-decodes the varied phoneme sequence to produce a word phoneme sequence by using the varied phoneme sequence and a preset DHMM (Discrete Hidden Markov Model) based context-dependent error model.