Gas sensing technology can detect gas concentration with high sensitivity and has significant application demands in the fields such as atmospheric chemistry, hazardous gas monitoring, etc. Compared with the non-spectral gas sensing technology, spectral technology utilizes the characteristic fingerprint spectrum of gas molecules, so it has excellent selectivity. The traditional photoacoustic spectroscopy technology employs the microphone as the acoustic detection element. However, the problems of the microphone itself, such as low Q value, wide response band, large background noise, and the large volume of the photoacoustic cell, restrict the practical application of this technology. In contrast to this, Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) and Light-Induced Thermoelastic Spectroscopy (LITES) take the Quartz Tuning Fork (QTF) as the acoustic wave detection element and light energy detection element respectively. Due to QTF having the characteristics of a narrow response frequency band (~4 Hz), high Q value (~10 000), an unnecessary photoacoustic cell, and so on, QEPAS has the advantages of anti-noise, small size, compact structure, low price, and so on, while LITES also has the advantage of non-contact detection. QEPAS and LITES have developed rapidly in recent years, and it has become a hotspot in gas sensing. Considering that both QEPAS and LITES technology can generate photoacoustic signals in the experiment and microresonators are usually devoted to increasing the acoustic signal strength. Therefore, in this manuscript, based on the resonance enhancement effect between the incident acoustic wave and the reflected acoustic wave, a non-one-dimensional resonant cylindrical cavity was designed to enhance the signal strength of the sensing systems and is first applied in out-of-plane incident QEPAS and LITES techniques. Firstly, the simulation model of QTF was established using the QTF size with the standard frequency of 32.768 kHz and was defined as a piezoelectric material. A cylindrical cavity was constructed near the QTF. Subsequently, the finite element analysis method was used in this paper. With and without adding the cylindrical cavity, respectively, to theoretically simulate and optimize the swing amplitude of the QTF and the position of the cylindrical cavity. The simulation results show that the QTF amplitudes in QEPAS and LITES are increased by 3.7 times and 1.9 times, respectively, after the addition of cylindrical cavities, compared with bare QTF. The experimental research, used a QTF with a standard resonant frequency of 32.768 kHz. Water vapour was selected as the target gas to test system performance, and its spectral line at 7 168.43 cm^-1 with a line intensity of 1.196×10^-20 cm/molecule was chosen as the target line to avoid interference from other gases in the air. A diode laser with an emission wavelength of 1.395 μm was adopted as the excitation source to match the water vapour absorption line. At this time, the output power of the laser was 18.9 mW. The low-frequency sawtooth wave output by a signal generator was employed for the coverage of the water vapour absorption line. The high-frequency sine wave generated by a lock-in amplifier was used to modulate the output wavelength. The two signals were superimposed and fed to the laser driver. The lock-in amplifier also demodulated the piezoelectric signal generated by QTF into the second harmonic signal, and its integration time and rolling coefficient were set as 100 ms and 18 dB/oct, respectively. To obtain the best response from the system, all experimental results were measured at the resonance frequency of the QTF and the optimum modulation depth (0.43 cm^-1). To make full use of the acoustic waves generated by the photoacoustic effect, the cylindrical cavity was made of 304 stainless steel material with high reflectivity, and a small hole slightly larger than the size of the QTF was machined on the side of the cylindrical cavity so that the QTF can be put into the cavity. The Minimum Detection Limits (MDL) of QEPAS and LITES systems with the cylindrical cavity were 17.27 ppm and 7.21 ppm respectively. Compared to the bare QTF system without the cylindrical cavity, the performance is improved by 2.32 times and 1.27 times. The experimental result is slightly different from the theoretical simulation result, caused by the deviation of the mesh division degree in the simulation, the piezoelectric conversion efficiency and the resonance frequency of the QTF from the actual.