A high-performance aldehyde sensor is of great significance for the detection of construction machinery exhaust gas and the analysis of environmental gas. Herein, we developed a novel aerogel SERS substrate of 4-Aminothiophenol (4-ATP) decorated three-dimensional (3D) porous structure using graphene oxide (GO), Au nanoparticles (Au NPs) and MXene as precursors. Benefiting from the synergistic effect of metal conductivity of MXene, the oxygen-enriched surface of GO and the high-density of “hot spots” (Au NPs), the 3D MXene/Au/GO/4-ATP aerogel structure exhibits enhanced capture efficiency of gaseous aldehyde and plasma enhancement for in-situ aldehyde gas detection. More importantly, a hot-blowing assisted SERS detection device was designed for gaseous aldehydes sensing. The SERS detection device responses to gaseous aldehyde molecules in simulated exhaust gas, offering fast detection time, high sensitivity, excellent reproducibility, and distinct selectivity. This work provides a potential strategy for monitoring harmful emissions, and promotes the design of a multi-functional SERS platform for complex gas sensing. • A novel MXene/Au/GO aerogel SERS substrate was successfully prepared. • The aerogel SERS substrate shows high SERS activity, reproducibility, and stability. • A hot-blowing assisted SERS device was developed for aldehyde detection in construction machinery exhaust. • The SERS detection device enables highly sensitive and selective aldehydes gas detection.