In Chinese culture, the word for "dust" (尘, chén) is homophonous with the word for "old" or "past" (陈, chén). To sweep away the dust is therefore to sweep away the troubles, misfortunes, and accumulated negativity of the previous year — clearing the way for fresh starts and incoming blessings.
The tradition is rooted in the belief that good and bad luck can become embedded in a household over time. A thorough cleaning physically dislodges this stagnant energy and makes space for the Kitchen God's positive annual report and the arrival of new prosperity.