Abstract: There is a widely held belief that the character "ruan" in "Mengruan", which is CAO Xueqin's courtesy name, refers to RUAN Ji who was a representative figure of the Wei and Jin Dynasties. It is believed that Meng Ruan expresses CAO's admiration for RUAN or the style of that time represented by RUAN. However, the evidence for this is insufficient. RUAN should refer to the surname of another family. Through in-depth research, it has been found that RUAN is actually a family name, which refers to the RUANs from Chenliu (currently in Kaifeng, Henan Province) in the Wei and Jin Dynasties, known for their indulgent drinking, as described in the book A New Account of Tales of the World. "Mengruan" is not a pseudonym, but a name that CAO gave himself. Its meaning reflects his admiration for the RUAN family's unrestrained drinking propensity, which is consistent with his own rebellious and unconventional personality. It also reflects the influence of the Daoist philosophy advocated by ZHUANG Zi and new Daoist in the two Dynasties, embodying CAO's pursuit for respect of nature, and innate freedom of life.