In this paper, we present the cross-talk modeling of the switching matrix based on XPM in SOA for optical packet-switched networks. Cross-talk-induced bit error rate (BER) and switch cascaded capability under unbalanced traffic are examined, which proves to be relevant to the SOA parameters, the traffic model unbalanced degree, the control pulse energy and so on. Several rules are drawn to facilitate the design of SOA-based switching matrix under unbalanced traffic.