Magnetic kagome crystals, consisting of corner-sharing triangles, is an intriguing class of ma- terials in condensed-matter physics as they host quantum spin liquid, Chern gapped topological fermions, electronic flat bands. The co-existence of geometric frustration and strong electron- electron correlations makes many kagome-lattice based systems an ideal system to study the inter- play between magnetism and topology for next-generation spintronics. For example, kagome mag- net such as YMn6Sn6 crystallizes into distorted, Mn-based stacking of kagome lattices compared to their pristine counterparts. We report a spin reconstruction in YMn6Sn6 from antiferromagnet to an incommensurate spin spiral phase originated from frustrated exchanges along the easy axis. Additionally, symmetry plays the role in hosting topological electronic properties, which also yields a fertile ground for the investigation of novel topological behavior in magnon. Our study provides a platform to understand the topological magnon stemming from the Mn-based kagome lattice in the spin-spiral phase of YMn6Sn6. Using a composite study, we demonstrate the accuracy of our prediction by highlighting experimental features.?