A demodulating method and a demodulating apparatus at a receiver based on a downlink transmit diversity mode in a LTE system are provided by the present invention. The method includes: dividing received data from sub-carriers of each receiving antenna based on a transmit diversity mode into multiple groups of received data according to numbers of antennas of a transmitter and a receiver; performing an independent demodulation on each group of the multiple groups of received data separately according to a demodulation algorithm of two-port transmitting and single-port receiving, so as to obtain a corresponding group of demodulated data; and for multiple groups of demodulated data corresponding to same transmitted data, performing a maximum ratio combination on the multiple groups of demodulated data according to a channel condition corresponding to each group of the multiple groups of demodulated data, so as to obtain a corresponding final demodulated data value. The demodulating method and the demodulating apparatus of the present invention can ensure the performance of the system adopting the diversity algorithm in situations of various kinds of antenna configurations, reduce cost and the complexity of devices in a practical application, and is very easy for project implementation.