Herein, a composite with heterogeneous porous structure composed of layered ZnFe2O4 grown on porous ZnO sheets (ZnO/ZFO composite) was synthesized by combining facile solvothermal and solution growth methods. The effect of solution growth time on ZnO/ZFO composites morphology was investigated and their gas sensing properties was compared. The result indicated the ZnO/ZFO composites sensors, especially the one with a growth time of 30 min showed significant improved gas sensing performance to triethylamine (TEA) compared with that of pure ZnO sheets, ZnFe2O4 and other ZnO/ZFO composites. Its response value to 100 ppm TEA was as high as 78 at 240 °C with good stability and repeatability, and the detection limit was as low as 0.5 ppm. The synergism of rich heterojunctions, increased oxygen-related vacancy species and porous structure would result in the excellent TEA sensing performance of ZnO/ZFO composite.