The development of a high-property ammonia gas sensor is of great significance for human health and environmental protection. Herein, MgFe2O4 nanomaterial was synthesized by a sol-gel method, and then a series of Ti3C2Tx-MgFe2O4 composites were prepared by an ethanol ultrasonic dispersion method. The structure and morphology of Ti3C2Tx-MgFe2O4 composites were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The gas sensing performance of the sensors based on different ratios of Ti3C2Tx-MgFe2O4 composites was investigated. The result shows that the gas response of 2.5% (in mass) Ti3C2Tx-MgFe2O4 composite (Ra/Rg=4.7) to 100 μL/L ammonia at 25 ℃ is 3.6 times greater than that of pristine MgFe2O4 nanomaterial (Ra/Rg=1.3). Meanwhile, this composite exhibits superior selectivity and fast response/recovery durations (i.e., 10.8 s/6.6 s).