1. A system for multi-lingual speech recognition, comprising: a digital signal processing unit; a speech modeling system, receiving and transferring a mixed multi-lingual speech signal into a plurality of speech features; a multi-lingual baseform mapping engine, comparing a plurality of multi-lingual query commands to obtain a plurality of multi-lingual baseforms; a cross-lingual diphone model generation engine executed by the digital signal processing unit, coupled to the multi-lingual baseform mapping engine, selecting and combining the multi-lingual baseforms, further comprising: fixing left contexts of the multi-lingual baseforms and mapping right contexts of the multi-lingual baseforms to obtain a mapping result; fixing right context and mapping the left contexts of the multi-lingual baseforms to obtain the mapping result if the contexts of the multi-lingual baseforms mapping fails; and obtaining the multi-lingual context-speech mapping data according to the mapping result; storing the multi-lingual context-speech mapping data in a multi-lingual model database; a speech search engine, coupled to the speech modeling engine, receiving the speech features, and locating and comparing a plurality of candidate data sets corresponding to the speech features according to the multi-lingual model database to find match probability of a plurality of candidate speech models of the candidate data sets; and a decision reaction engine, coupled to the speech search engine, selecting a plurality of resulting speech models corresponding to the speech features according to the match probability from the candidate speech models to generate a speech command.