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NGC 1566 is a changing look AGN known to exhibit recurrent X-ray outburstswith each lasting for several years. The most recent X-ray outburst is observedon 2018, with a substantial increase of 2--10 keV flux by a factor of ~24 thanthe historical minimum. We re-analyze the XMM-Newton and NuSTAR observationscovering the pre-outburst, outburst and post-outburst epochs, and confirm thediscovery of the broad feature in the ~5--7 keV band during the period ofoutburst that could be interpreted as a relativistic Fe K_alpha emission line.Our analysis suggests that its flux has increased in tandem with the 2--10 keVcontinuum, making it the second changing look AGN in which the broad Fe K_alphaline responds to the X-ray continuum variability. This behavior stronglysupports the idea that X-rays originates in a corona above the accretion disk,and disk reflection produces the relativistic Fe K_alpha line. In addition, wefind the response of narrow Fe K_alpha emission line to the changes in theX-ray continuum on a time-scale as short as four months, allowing to put thelocation of line-emitting region at <0.1 pc, comparable to the size of opticalBLR. By comparing to the changing look AGN NGC 2992, the Fe K_alpha variationrate (the ratio of Fe K_alpha variation to luminosity variation) in NGC 1566appears greater, which could be possibly explained by larger amount of gas orFe abundance responsible for producing the Fe K_alpha line for the latter. Thestrength of variable broad Fe K_alpha line as well as the soft X-ray excessemission appears to be correlated with the accretion rate, which could beexplained as due to the state transition associated with the changing-lookphenomenon.

Response of the Fe K_alpha line emission to the X-ray continuum variability in the changing-look active galactic nucleus NGC 1566