Low-frequency resistance noise spectroscopy is applied to investigate bulk single crystals of the intercalated iron-selenide KxFe2-ySe2 superconductors with different iron vacancy orders.Based on a generalized fluctuation model,the well-observed resistance hump above 100 K is interpreted as an insulator-metal phase transition with a characteristic tran-sition energy of 0.1-0.6 eV,indicating a highly inhomogeneous energy distribution configuration.In the superconducting transition regime,we find that the normalized resistance noise scales with resistance R excellently as SR/R2 ∝Rlrs with the noise exponent lrs ≈ 1.4.With reduced iron vacancy disordering in enhanced superconductivity KxFe2-ySe2 crystals,the level of resistance fluctuations is greatly suppressed,suggesting a geometrical phase transition for conduction channel,which is directly related to the microstructure of the crystals.