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The overwhelming foreground contamination hinders the accurate detection ofthe 21-cm signal of neutral hydrogen during the Epoch of Reionization (EoR).Among various foreground components, the Galactic free-free emission is lessstudied, so that its impact on the EoR observations remains unclear. In thiswork, we employ the observed $\rm H\alpha$ intensity map with the correction ofdust absorption and scattering, the Simfast21 software, and the latest SKA1-Lowlayout configuration to simulate the SKA "observed" images of Galacticfree-free emission and the EoR signal. By calculating the one-dimensional powerspectra from the simulated image cubes, we find that the Galactic free-freeemission is about $10^{3.5}$-$10^{2.0}$, $10^{3.0}$-$10^{1.3}$, and$10^{2.5}$-$10^{1.0}$ times more luminous than the EoR signal on scales of$0.1~\rm Mpc^{-1} < k < 2~\rm Mpc^{-1}$ in the $116$-$124$, $146$-$154$, and$186$-$194$ ${\rm MHz}$ frequency bands. We further analyse the two-dimensionalpower spectra inside the properly defined EoR window and find that the leakedGalactic free-free emission can still cause non-negligible contamination, asthe ratios of its power (amplitude squared) to the EoR signal power can reachabout $200\%$, $60\%$, and $15\%$ on scales of $1.2~\rm Mpc^{-1}$ in threefrequency bands, respectively. Therefore, we conclude that the Galacticfree-free emission, as a severe contaminating foreground component, needs to becarefully treated in the forthcoming deep EoR observations.

Contribution of Galactic free-free emission to the foreground for EoR signal in SKA experiments