In this paper, a novel QAM constellation division based user grouping communication scheme is proposed for the massive MIMO uplink systems. In the proposed scheme, orthogonal pilot sequences are assigned to adjacent cells to eliminate the pilot contamination between adjacent cells, while the users in the same cell are divided into groups and each group uses one pilot sequence. In each group, a QAM constellation is divided into two PAM constellations for the two users to implement uplink transmission. With the help of the pilot sequences, the base station (BS) firstly estimates the sum channel of each group, and then executes signal detection by adopting the matched filter detector based on the estimated sum channel as well as the asymptotic orthogonality between different channels while the number of BS antennas goes to infinity. Furthermore, the effect of the large-scale fading coefficients of the channels on the average symbol error rate (SER) of all the users is investigated, and an explicit and concrete user grouping approach is proposed to decrease the average SER. Finally, computer simulations illustrate that our proposed communication scheme performs well and the proposed user grouping approach is obviously effective.