  The precursors of short and long Gamma Ray Bursts (SGRBs and LGRBs) can serve
as probes of their progenitors, as well as shedding light on the physical
processes of mergers or core-collapse supernovae. Some models predict the
possible existence of Quasi-Periodically Oscillations (QPO) in the precursors
of SGRBs. Although many previous studies have performed QPO search in the main
emission of SGRBs and LGRBs, so far there was no systematic QPO search in their
precursors. In this work, we perform a detailed QPO search in the precursors of
SGRBs and LGRBs detected by Fermi/GBM from 2008 to 2019 using the power density
spectrum (PDS) in frequency domain and Gaussian processes (GP) in time domain.
We do not find any convinced QPO signal with significance above 3 $\sigma$,
possibly due to the low fluxes of precursors. Finally, the PDS continuum
properties of both the precursors and main emissions are also studied for the
first time, and no significant difference is found in the distributions of the
PDS slope for precursors and main emissions in both SGRBs and LGRBs.
