Karst geology has great influence on the construction and operational maintenance of shieldbored Metro tunnels and cutandcover structures. The karst geological conditions encountered in Guangzhou Metro construction can be divided into high risk area and low risk area. The karst carve in high risk area must be filled up. Taking the design of the karst treatment of the north extension section of No. 3 line of Guangzhou Metro as an example, the author presents the treatment intention, treatment principle, treatment measures, construction attention items and test standards in detail. The karst treatment measures are divided into measures for shield tunnel sections and measures for cutandcover structures.