The custom is also called as "Shao Chen" in Chinese. "Shao" means sweeping. "Chen" means dirt. "Chen" is a homophone of "the old things", so the custom has the implicit meaning as sweeping away the old things. This meaning compliances just with the meaning of Chinese New Year, that is, cleaning away all the bad lucks in the old year.
On the 24th of lunar December, every Chinese family washes their house, fornitures, vessels, bedclothes, etc. and cleans the environment around. People are busy and happy. The festive atmosphere has become very strong at the time.