Monitoring and detecting triethylamine (TEA) vapor are essential in the organic synthesis industry. Two-dimensional Co₃O₄nanosheets with large surface areas and multiple active sites are ideal for fabricating chemiresistive gas sensors. However, the face-to-face stacking owing to the high surface energy of nanosheets, would cover up the active sites, obstruct gas diffusion, raise contact resistance, which all hinder its utilization for TEA detection. Herein, the Co₃O₄mesoporous nanosheets were assembled into hierarchical microspheres by adding the structure-directing agent PVP K30 and combined with a proper annealing temperature, whichoptimized their grain size, specific surface area, pores structure, oxygen vacancies, and the atomic ratio of Co²⁺to Co³⁺.And these ultimatelyimproved the detection capability of TEA.The sensor based on Co₃O₄sphere-300 exhibits the highest sensor response of 34.1 to 100 ppm TEA and a low detection limit (0.5 ppm) at a low working temperature of 150°C.The promising properties are mainly due to the combination of several advantages that facilitate simultaneous chemical and electronic sensitization. This work prepared a high-performance TEA gas sensor and verified the improvement of comprehensive sensitization on the gas-sensing performance of two-dimensional metal oxide semiconductors.