Embodiments of the present invention provides an adaptive space-time coding and modulation method and a transmitter. In one embodiment, the method includes: obtaining a curve corresponding to a modulation mode, a channel coding rate, a coding mode of a space-time code, a parameter indicating signal transmission quality and SNR by simulating or measuring at transmit-side and making a table with correspondences between the SNR, the modulation mode and the coding mode of the space-time code according to a SNR range corresponding to a predefined signal transmission quality. Higher frequency spectrum efficiency can be achieved with the quality of service guaranteed.