A new drift tube structure for proton transfer reaction mass spectrometry, called conical funnel drift tube, is designed in this work, which is composed of 20 traditional ring electrodes and 5 new conical electrodes. Firstly, the ion focusing effect of the new drift tube is verified by ion trajectory simulation, and then further comparative experiments are conducted to validate the performance of the new drift tube. The results show that the new conical funnel drift tube has a softer ionization effect and higher sensitivity (4.0–6.3 times) than the traditional drift tube. Moreover, different from the traditional RF focusing method, the new conical funnel drift tube can realize ion focusing only through DC electric field without the need of additional RF power supply, making it especially suitable for instruments requiring miniaturization and low power consumption to improve detection sensitivity.