Abstract: A study is reported in which the design features and field results of a multi combination test probe system were discussed to evaluate efficiency of buried pipeline cathodic protection. The system is useful in measuring current"on"protection potential(U_on), IR drop in pipe-to-soil potential, current"off"protection potential(U_off), current density (i_p), corrosion potential(U_corr), potential drift at current"on"and"off"(ΔU_onand ΔU_off) and current density(i_corr)。The instrument is ideal for pipeline corrosion test.