Long-term buried ground copper sulfate reference electrode: mainly used in the cathodic protection potential measure of long term pipeline and storage tank floor plate. Portable copper sulfate reference electrode: which is suitable to spot use, mainly used in measuring the natural potential and cathodic protection potential of underground metal pipelines, measuring stray current of soil, also used in measuring potential of cable metal sheath and reinforcement in concrete. The electrode in the soil is more sticky, can be used as the reference electrode for control potential in impressed current cathodic protection system, it also can be used in various types of soil and fresh water, such as the measurement of cathodic protection system for storage tanks, buried pipes, reinforced concrete, wharf and other structures.