Coalescer are commonly utilized in the realm of deep gas drying field, and its performance is contingent upon the filter. The filter consists of a support structure, a coalescing layer, and a drainage layer. However, research focuses more on the impact of coalescing and drainage layers on coalescence performance. The impact of the support structure and the interlayer gap of the coalescing layer on coalescence performance during the production process remains unknown. To address the issue, the experiments were performed under 0.30 m/s surface velocity and 2.50 g/min liquid loading rate with coalescing layer ranging from 1 to 6 layers. Variation of pressure drop under different supports identified a statistically significant advantage for diamond mesh over orifice. The three placement methods' specific order of pressure drop is both-sided > front-side> no-support > back-side placement. Based on experimental evidence showing that liquid film interception of droplets dominates in the coalescence process, the liquid film interception theory was proposed. Further, based on the "liquid film interception theory", the effect of interlayer gaps on coalescence performance was researched. The results show that setting interlayer gaps corresponds to an increase in separation efficiency by 1–4 %, an increase in wet pressure drop by 34.63–63.86 %, and a decrease in quality factor by 208.76 %. Therefore, to achieve high-performance filter media, interlayer gaps should be avoided during the manufacturing process.