Sun Suzhen (孫素真) (16 October 1895 - 4 April 1975) was the 18th matriarch of I-Kuan Tao. She was the successor of Zhang Tianran, I-Kuan Tao's contemporary founder as well as Zhang's third wife. Sun was also known as Ming Shan (明善) or Hui Ming (慧明), her religious name.
Sun was born in Shan County, Shandong province on the 28th day of the eighth lunar month in 1895. She was introduced to I-Kuan Tao in 1908 and became the student of Lu Zhongyi, there she met Zhang Tianran. Zhang took her as his second wife (in name only, because it was inappropriate for an unwed woman to be seen traveling around with a man unescorted, the fake marriage was to eliminate rumours and staining Sun's name), which was believed to be Heaven's will and lifted her as the incarnation of Bodhisattva Yue Huei (Moon Wisdom), the counterpart of Ji Gong. Her followers regarded her to hold the seat of the 18th patriarch together with Zhang in 1930.
After the death of Zhang in 1947, she took control of I-Kuan Tao. Many of Zhang's followers followed her leadership. Only a small fraction stayed on with Madame Liu, the second wife of Zhang.
In Hong Kong she was said to have left behind a large number of heavenly mandates (天命). To this day, there are a few elders in Hong Kong who are believed to be the keepers of these heavenly mandates.
In 1954, she moved to Taiwan. Because I-Kuan Tao was illegal then, she kept a low profile and was kept under seclusion. She was sick in the last years and under the care of a nun surnamed Zhou in Taichung. Later she was under the care of Wang Hao De until her death. She died on the 23rd day of the second lunar month in 1975 (4 April 1975) one day before the death of Chiang Kai-shek.
- David Jordan & Daniel Overmyer. 1985. The Flying Phoenix: Aspects of Chinese Sectarianism in Taiwan. Princeton University Press.
- Soo Khin Wah. 1997. A Study of the Yiguan Dao (Unity Sect) and its Development in Peninsular Malaysia. Ph.D. dissertation, University of British Columbia.
- History of Sun Su Zhen according to her followers
- The patriarch of I Kuan Tao
- History of I Kuan Tao according to the followers