To study thermal comfort under task/ambient conditioning (TAC) system, equivalent temperature (EQT) index was used to evaluate local and overall thermal sensation under non-uniform thermal environment. From the “human subject test in a mockup office”, local thermal sensations and equivalent temperatures under different stimulated conditions were collected. It is found that thermal sensation and equivalent temperature have a good linear relationship. EQT comfort zone of the TAC in non-uniform environment was drawn through the fitting method. The findings are of significance on the design and operation of TAC system.