Since the discovery of graphene materials, two-dimensional materials have been widely recognized and gradually applied. Two-dimensional transition metal carbides (MXenes) have better mechanical, magnetic and electrical properties than traditional two-dimensional materials. In this work, Ti ₃C ₂T _xsamples are prepared by etching Ti ₃AlC ₂with different etching agents for the solutions of HF and LiF/HCl. The effects of etching agents on the structure and gas sensing properties of Ti ₃C ₂T _xmaterials are studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and gas sensing properties analysis. The material structure analysis shows that both HF and LiF/HCl etching agents have good etching effect on Ti ₃C ₂T _xmaterial. The results of gas sensing properties show that the gas sensing properties of Ti ₃C ₂T _xprepared by LiF/HCl etching agent is better than by HF etching agent, and the wide range, high sensitivity and high stability of NH ₃detection can be achieved at room temperature. The analysis shows that the high sensing performance of Ti ₃C ₂T _xprepared by LiF/HCl solution etching is mainly due to the high proportion of —O and —OH functional groups on the surface of Ti ₃C ₂T _x. The experimental studies can lay a theoretical foundation for studying the gas sensing and practical application of Ti ₃C ₂T _xbased sensor.