Abstract. Migration of legacy systems to SOA has caught lots of attention in both academic and industry. People have proposed many methods, such as wrapping, reengineering etc. However, various characteristics of legacy systems can make the migration complicated, and different enterprises can afford different level migration cost. In this paper, the existing methods and options for evolving legacy systems are compared, and their advantages and disadvantages are identified respectively. Different adaptive situations are listed to assist in making migration decision.