Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe₂O₃ nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt₁-Fe₂O₃-ox) exhibited a high response (R_a/R_g =102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe₂O₃ support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).