In this work, hierarchical porous SnO2/Zn2SnO4 composites were synthesized via a facile one-step hydrothermal method with subsequent heat treatment. Many methods were performed to investigate the crystalline and morphological characterization of the as-prepared composite. The gas sensors based on the porous SnO2/Zn2SnO4 composite were fabricated and their gas sensing performance was systematically investigated. Significantly, compared with the pure SnO2 and Zn2SnO4 solid particles, the hierarchical SnO2/Zn2SnO4 porous spheres exhibited excellent gas sensing properties toward triethylamine (TEA). The response value was 48 toward 100 ppm TEA, and the detection limit could be down to 500 ppb with a response value of 1.4. The excellent gas sensing properties are contributed to the porous nanostructure and the heterojunction between SnO2 and Zn2SnO4 composite.