The invention discloses a Mongolian large vocabulary continuous speech recognition method. The method is composed of a preprocessing phase, a preparation phase, a training phase, a decoding phase and a synthesis conversion phase. In the preprocessing phase, text training data is segmented and a pronunciation dictionary is established; in the preparation phase, acoustic features are extracted from input voice signals; in the training phase, an acoustic model is trained by use of a whole-word pronunciation dictionary, and a language model is trained by use of a training text after segmentation; in the decoding phase, by use of the acoustic model, the language model and the pronunciation dictionary, the input acoustic features are recognized into text information; and in the synthesis conversion phase, case suffix errors in a decoding process are corrected by use of rules, stems are merged with case suffixes, and finally, sentences composed of Mongolian words are output. According to the invention, the problems of too long voice recognition time and language model data sparsity in a voice recognition system because the voice recognition system cannot include large-scale Mongolian words and the vocabulary is too large in the prior art are solved.