  We study a blowout jet that occurs at the west limb of the Sun on August
29$^{th}$, 2014 using high-resolution imaging/spectroscopic observations
provided by SDO/AIA and IRIS. An inverse $\gamma$-shape flux-rope appears
before the jet{--} morphological indication of the onset of kink instability.
The twisted field lines of kink-unstable flux-rope reconnect at its bright knot
and launch the blowout jet at $\approx$06:30:43 UT with an average speed of 234
km s$^{-1}$. Just after the launch, the northern leg of the flux rope erupts
completely. The time-distance diagrams show multiple spikes or bright dots,
which is the result of periodic fluctuations, i.e., quasi-periodic fluctuations
(QPPs). The wavelet analysis confirms that QPPs have a dominant period of
$\approx$ 03 minutes. IRIS spectra (Si~{\sc iv}, C~{\sc ii}, and Mg~{\sc ii})
may also indicate the occurrence of magnetic reconnection through existence of
broad $\&$ complex profiles and bi-directional flows in the jet. Further, we
have found that line broadening is periodic with a period of $\approx$ 03
minutes, and plasma upflow is always occurs when the line width is high, i.e.,
multiple reconnection may produce periodic line broadening. The EM curves also
show the same period of $\approx$ 03 minutes in different temperature bins. The
images and EM show that this jets spire is mainly cool
(chromospheric/transition region) rather than hot (coronal) material. Further,
line broadening, intensity, and EM curves have a period of $\approx$03 minutes,
which strongly supports that multiple magnetic reconnection triggers QPPs in
the blowout jet.
