2-dimensional (2D) block spread CDMA makes it possible to achieve multiple-access interference (MAI) free uplink transmission with low-complexity single-user detection and therefore is very attractive. In this paper, we propose a code assignment algorithm for 2D block spread CDMA uplink in multi-cell systems. It is shown by the computer simulation that in the frequency-selective fading channel, the code reuse coefficient achieved by the proposed code algorithm is about four times that of traditional algorithms, while satisfying the requirement of quality of service (QoS).