Based on engineering quality classification of rock mass, support classification is carried out and a classification method is put forward for underground workings, taken into comprehensive account the service time, exposure area and influence extent of the workings. It is concluded that support cost could be reduced when varied support means are used to justify workings of different support grades. This approach has been adopted in Chengchao Iron Mine for support of preparatory workings. Application results indicate that it is significant to guarantee the support quality and cut down support cost through support classification.