1. A method for recognizing a speech, comprising: receiving, by a media resource processing device, an H.248 message carrying a speech recognition instruction and a related parameter sent by a media resource control device, wherein the related parameter comprises a recognition grammar parameter for the speech, the recognition grammar parameter for the speech is a recognition grammar for a common speech; performing, by the media resource processing device, speech recognition according to the speech recognition instruction and the related parameter; and reporting a recognition result to the media resource control device, the method further comprise: extracting, by the media resource processing device, a text string and performing the speech recognition after receiving the recognition grammar parameter, wherein a specific character string is embedded into the recognition grammar parameter.