The invention provides a joint iterative detection decoding method. The method comprises the following steps of: a, according to the number of vectors of the signals needing to be detected in the joint iterative detection, a modulation module(M) of a transmitting antenna and the number of receiving and transmitting antennas, determining the number(cj) of optional constellation points corresponding to each transmitting antenna, wherein the cj is less than or equal to 2; b, obtaining a matrix(R) and a unitary matrix(Q) by performing the upper triangularization treatment of a current channel matrix, and weighting the current receive signal(y) by utilizing a conjugation device(Q) of the matrix(Q) to obtain a weighting receive signal (y' is equal to Qy); c, selecting the constellation points for all transmitting antennas step by step in a tree searching mode so as to form the detection signal vectors in an alternate collection list; and d, calculating the log likelihood ratio of each bit of information by utilizing the MAP bit detection algorithm according to all detection signal vectors in the alternate collection list. The invention also provides a joint iterative detection decoding device. The application of the device and the method can reduce the complexity of the joint iterative detection decoding and ensure the detection performance as well.