An apparatus and a method for transmitting and receiving data in a mobile communication system including an array antenna. The method includes the steps of transmitting pilot channels through a transmission antenna while aligning the pilot channels orthogonally to each other, receiving feedback information related to the pilot channels from a mobile station capable of receiving the data, dividing the data to be transmitted into sub-data streams by using the feedback information, and determining a coding rate and a transmit power for the sub-data streams, and converting the sub-data streams into symbol arrays to be transmitted according to the coding rate and the transmit power and transmitting data by converting the data into fixed beams.