"Shui long yin: Visiting the Shangxin Pavilion in Jiankang," a masterpiece of Xin Qiji's ci poem, has long been controversial for its time of composition. There are three major opinions: Liang Qichao asserts that it was composed when Xin was thirty years old, Deng Guangming claims he was then thirty-five, while Cai Yijiang contends that it is a creation when Xin was twenty-eight. Besides analyzing the work in detail, this paper also takes into consideration the related historical facts and materials on Xin's life. It demonstrates that none of the above opinions is tenable, and concludes that the piece was composed during the period when Xin was aged between 41 and 48.