The cable must be tested in cyclic heating condition for a long-time period according to the national standard before the delivery. By cyclic heating test, the actual current-carrying capacity of the cable is determined. In this paper, the cable cyclic heating system and temperature control technology is studied. In regard to the relation between heating temperature in working condition and ampacity of large-lag cable core, symbolic method-based temperature control approach is designed, which realizes the adaptive temperature control process of long-time constant lag system and meets the demand of cable temperature control in the field environment test.