We report the results from pulsations and spectral analysis of a large number of observations of the HMXB pulsar IGR J18027--2016 with {it Swift}--XRT, carried out at different orbital phases. In some orbital phases, as seen in different XRT observations, the X-ray intensity is found to vary by a large factor, of about $sim$50. In all the observations with sufficient number of source X-ray photons, pulsations have been detected around the previously known pulse period of $sim$140 sec, When detected, the pulse profiles do not show any significant variation over a flux difference of a factor of $sim$3. The absorption column density is found to be large before and after the eclipse. We discuss various possible reasons for intensity and spectral variations in IGR J18027--2016, such as clumpy wind and hydrodynamic instabilities.
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