The original name of the broadsword is Heavy-Knife of martial arts, which is a traditional weapon in the areas of Beijing and Tianjin, which existed in China for thousands of years. Hui-nationality Heavy-Knife in Tianjin became famous in the early years of Emperor Yongle in Ming dynasty. According to legend, one of Zhu Li (King Yan)'s general of Hui-nationality from Jinling used a 30-kilogram broadsword to fight. After the suppression of Tianjin by Zhu Li's northern expedition, he moved his family there, so the Tianjin Cao's Broadsword was born and handed down from generation to generation. In modern times, the broadsword of successor Imam Cao Jinzao weighs up to 80 kilograms, and has become a fitness equipment. Cao Jinzao also integrated the Chinese boxing styles from "Northern Shaolin", "Western Boxing" and the fist-position of ancestors to form the so-called "72-style chained boxing" with southern style boxing, northern footwork, wrestling and catching all in one, among which three movements and postures count the most. Cao Jinzao's martial arts stood out conspicuously, and he had a strong sense of justice and ready to help the weak, so he was named "Two Chivalries from Han and Hui Nationalities" with Huo Yuanjia. Cao Jinzao's son, Cao Keming, inherited his father's cause and established himself "Cao's knife style" on the basis of martial arts of the Cao's family. With the aim of "promoting martial arts, body building and country protecting", he established the first martial club of Hui nationality in Tianjin. Now, the club has been passed down to the brothers Cao Shiwei and Cao Shijie, and the inheritance method has also changed from being "hereditary" to open teaching.

Since the Tang dynasty, 80 kilograms of heavy knives were the main equipments for the martial arts examinations. Cao's knife style adopts the subjects from past martial arts examinations and mixes other martial arts into the movements and postures of the heavy knives. Cao's heavy knife mainly includes the knife styles of inserting, carrying, screwing, pyramiding, etc. It combines hardness and softness, being dynamic and static while integrating strength and skill at the same time.

The broadsword dances, moving like wind, still as pine trees; though weighing a lot when carrying, it can be as light as a feather when waving. The steel ring sounds aloud when the broadsword is raised and in silence when put down. Breathtaking yet graceful, it is a real feast to the eyes.  

Cao's knife style has been widely praised by people from all walks of life at home and abroad for its purpose of carrying forward the spirit of national martial arts, strengthening national unity, and building the body by practicing Kong Fu. At present, this important martial skill encounters problems like insufficient funds and lack of space in its development, which demand urgent solutions.