The invention discloses a transmission method adapted in a mixed carrier CDMA (Code Division Multiple Access) transmission system, relating to the field of wireless communication, solving the problem of higher peak-to-average ratio of the traditional multi-carrier system and improving the system error-code performance under a selective fading channel. In the invention, on a sending end, sequence spreading is carried out on data of a certain order of fractional Fourier transform domain by adopting a CDMA technology, and the spread data is transformed to a time domain for transmission; and on a receiving end, according to the reversibility of weighted fractional Fourier transform, the data is transformed to the fractional Fourier transform domain again for sequence de-spreading so as to obtain output data. The mixed carrier CDMA transmission system is suitable for mixed carrier signal transmission.