Icy lunar regolith(ILR) exists in lunar permanently shadowed regions. The preparation of ILR simulant is crucial for conducting ground-based tests for in-situ resource utilization(ISRU). To improve the fidelity of ILR, a novel method for ILR preparation was introduced, termed the water molecule deposition coating(WMDC) method, anchored in the natural formation mechanism of ILR. The cold regolith particles undergo complete tumbling, effectively trapping the water molecules. ILR samples were evaluated for uniformity in water content and micro-morphological characteristics to substantiate the effectiveness of this method. The discrete element method(DEM) was used to analyze the motion and mixing processes of lunar regolith particles within a baffled rotary drum and to determine the impact of various conditions on particle flow behaviors. The results revealed positive correlations between rotation speed, baffle number, and filling degree with central particle density (CPD), with optimal mixing index (MI) achieved at higher rotation speeds and lower filling degrees.