The Sun-style (孫氏) t'ai chi ch'uan is well known for its smooth, flowing movements which omit the more physically vigorous crouching, leaping and fa jin of some other styles. The footwork of Sun style is unique, when one foot advances or retreats the other follows. It also exhibits small circular movements with the hand. Its gentle postures and high stances make it very suitable for geriatric exercise and martial arts therapy.
Sun style t'ai chi ch'uan was developed by Sun Lutang, who was considered expert in two other internal martial arts styles: xingyiquan and baguazhang before he came to study t'ai chi ch'uan. Today, Sun-style ranks fourth in popularity and fifth in terms of seniority among the five family styles of t'ai chi ch'uan. He was also considered an accomplished Neo-Confucian and Taoist scholar, especially in the Yi Jing and the T'ai chi classics. Sun learned Wu (Hao)-style t'ai chi ch'uan from Hao Weizhen, who was Li Yiyu's (李亦畬) chief disciple.
Besides his earlier xingyi and bagua training, Sun's experiences with Hao Weizhen, Yang Shaohou, Yang Chengfu and Wu Jianquan influenced the development of what is today recognized as the Sun style of t'ai chi ch'uan. Sun's son Sun Cunzhou (孫存周; 1893—1963) and daughter, Sun Jianyun (孫劍雲; 1914—2003) were t'ai chi ch'uan teachers, as well as Sun Cunzhou's daughter Sun Shurong (孫淑容; 1918—2005) who taught in Beijing until her death. Sun Wanrong (孫婉容; 1927—Present) who is the other daughter of Sun Cunzhou still teaches t'ai chi ch'uan in Beijing now.