Her appearance was described as only above average.  Her complexion was noted to be snowy white. 
To an initial observer, Jiang Yanli's personality was mild, with nothing too notable.  She enjoyed cooking for others, especially her brothers,  and was implied to prefer cooking over cultivation. 
Underneath her gentle and polite exterior, however, Jiang Yanli was fiercely protective of her family. She refused to tolerate any insults towards her sworn brother Wei Wuxian, and she alone possessed the ability to reason with Wei Wuxian in the depths of his grief-stricken madness. Ultimately, she did not hesitate to sacrifice her life for her brother's.