The current study originally presents a detailed approach to implement the p-xylene based two-color PLIF for measuring gaseous mixture temperature and mole concentration field simultaneously. An 80 * 0.8mm(2) laser sheet at 266nm is employed to excite homogenous p-xylene/nitrogen steady mixture flow in a calibration cell, where the known p-xylene mole concentration and temperature are adjustable. Doing so, the full band/spectral (centered at 289nm) fluorescence intensity are respectively captured by ICCD camera that allows establishments of temperature-fluorescence ratio database. Concomitantly, the full band fluorescence intensity correlation with temperature and mole concentration is rightly created as well. Utilizing the identical laser sheet and detection channel, the quantitative temperature and mole concentration field in a far-field developed-spray region could be inferred by terms of full band/spectral fluorescence imaging through previous calibration database. The error propagation issue of temperature and mole concentration measurement by this approach are discussed. As a result, it is found that the relative temperature and mole concentration uncertainties are in the range of 5.4 similar to 7.3% and 8 similar to 9.3% (or 12.3 similar to 18.7% by bottom-up approach), respectively, within studied temperature range of 423 similar to 573K. Therefore, the suitability and capability of p-xylene as the tracer for spatio-temporal temperature and mole concentration measurements are preliminarily validated, which offers an alternative tracer option for gasoline/its surrogate spray studies. It is noted that replacing the p-xylene by other suitable fluorescence tracer, i.e.,1-methylnaphthalene, this approach could be rightly performed for studies of Diesel engine, or even gas turbine.