Abstract A standoff laser spectroscopy sensor based on a broadband tunable external cavity quantum cascade laser (ECQCL) and a piezoelectric effect-based detector was developed for simultaneous detection of multiple chemicals. Instead of using a standard infrared detector, a custom quartz crystal tuning fork (QCTF) with a high resonant frequency (∼75 kHz) was adopted as a light detector for laser signal collection. To explore the capabilities of this technique, the impact of the position of incident light beam excitation with respect to the QCTF on the signal amplitude, resonant frequency and Q-factor was observed in detail. In addition, the influence of incident light intensity and pressure on the intrinsic property of the QCTF was also systematically investigated. Finally, the ECQCL sensor was successfully demonstrated for the standoff detection of plumes for three volatile organic compounds (VOCs) (i.e., alcohol, acetone and ether) at a distance of 40 m, which proves the applicability of the technique for the detection of leak plumes in security fields.