  We report on timing and spectral analysis of transient Be X-ray pulsar GRO
J1750-27 by using the Nuclear Spectroscopic Telescope Array (NuSTAR)
observation from September 2021. This is the fourth outburst of the system
since 1995. The NuSTAR observation was performed during the rising phase of the
outburst. Pulsations at a period of 4.450710(1) s were observed in the 3-60 keV
energy range. The average pulse profile comprised of a broad peak with a weak
secondary peak which evolved with energy. We did not find any appreciable
variation in the X-ray emission during this observation. The broad-band
phase-averaged spectrum is described by a blackbody, a powerlaw or
Comptonization component. We report discovery of Fe K$_{\alpha}$ line at 6.4
keV along with presence of two cyclotron resonant scattering features around 36
and 42 keV. These lines indicate a magnetic field strength of
$3.7_{-0.3}^{+0.1} \times 10^{12}$ and $4.4 \pm 0.1 \times 10^{12}$ G for the
neutron star. We have estimated a source distance of $\sim$ 13.6-16.4 kpc based
on the accretion-disc torque models.
