1. A method for text to speech conversion, comprising: a text analysis step for parsing the text to obtain descriptive prosody annotations of the text based on a text to speech model generated from a first corpus; a prosody parameter prediction step for predicting the prosody parameter of the text according to the result of text analysis step; and a speech synthesis step for synthesizing speech of said text based on said predicted prosody parameter of the text; Wherein descriptive prosody annotations of the text include prosody structure of the text, the prosody structure of the text is adjusted according to a target speech speed for the synthesized speech.