The Sun style tai chi chuan was developed by Sun Lu-t'ang , who was considered expert in two other styles: and before he came to study tai chi chuan. Today, Sun style ranks fourth in popularity and fifth in terms of seniority among the five family styles of tai chi chuan. He was also considered an accomplished Neo-Confucian and Taoist scholar, especially in the I Ching and the tai chi classics. Sun learned from Hao Wei-chen , who was Li I-yü's chief disciple.
Besides his earlier hsing-i and pa kua training, Sun's experiences with Hao Wei-chen, Yang Shao-hou, Yang Ch'eng-fu and Wu Chien-ch'üan influenced the development of what is today recognized as the Sun style of tai chi chuan. Sun's son Sun Cunzhou and daughter, Sun Jianyun were tai chi chuan teachers, as well as Sun Cunzhou's daughter Sun Shurong who taught in Beijing until her death.
Sun style tai chi chuan is well known for its smooth, flowing movements which omit the more physically vigorous crouching, leaping and Fa jing of some other styles. The footwork of Sun style is unique, when one foot advances or retreats the other follows. It also uses an open palm throughout the entirety of its main form, and exhibits small circular movements with the hand. Its gentle postures and high stances make it very suitable for geriatric exercise and martial arts therapy.