Nowadays shield tunneling for metro tunnel is the mainstream technology of urban rail transit system construction. And environmentfriendly tunnel construction by shield is crucial to satisfy constant increasing urban environment protection requirements.Thus the environment protection during shield tunneling is studied in depth via the construction experiences of the tunnel section between Shiju station to Xiaoyucun station on No.3 line of Kunming metro. And then a harmonious relation between tunnel construction and surrounding environment protection is reached through the introduced pollutions sources characteristics and the effective and practical countermeasures for them. 