Onn Mann Liang was born in Canton (now Guangzhou), China on December 11, 1901. He attended the Kwangtung Engineering College and received a degree there and his major was in railroad engineering. In 1922 Liang began his nine year stay in America as a fruit picker at Walnut Grove in California while he was living in Berkeley, California. He moved to Michigan a year later. For the next five months, Liang worked at a Chevrolet plant in Flint before coming to East Lansing to begin his studies in Engineering. Liang attended Michigan State College (now Michigan State University) from September 22, 1924 to June 21, 1926. He was one of a group of twenty international students who studied at Michigan State in the 1920s. Liang graduated from MSC in 1926 with a B.S. in Engineering.

Immediately after completing his undergraduate studies, Liang began working for the Michigan State Highway Department. He was terminated on May 1, 1932 due to a decrease in the Department's budget, a result of the Great Depression. While working at the Department, Liang traveled to see the bridges and architectural feats of Chicago, Illinois, and Buffalo, New York.

In 1932 Liang returned to Canton, China, where he opened his own engineering firm. At the same time, he worked for the Canton government. Liang designed dykes and bridges throughout the country. Liang married Janet Yee on January 5, 1936. Liang's wife was a native of Taishan, China. Their first child, a son, was born in 1937. He died in December of 1941 due to an illness. Their second son was born in October 1948.

Liang briefly lived in Hong Kong, from 1938 to 1939, before returning to China. He lived in Kukong, China from 1939 to 1945. During World War II, Liang worked for the U.S. Army. From 1948 to 1949 Liang worked for the United States Economic Cooperation Administration Mission to China, where he did repair work on the Sun Kwong Dyke project. He designed and supervised the construction of the Maternity Ward and Nurses Dormitory of the Fong Pin Hospital. His job was terminated on May 13, 1949 because the Chinese Government was losing grounds to the Communist Party. Following that, he took a job with the Audio-Visual Educational Unit, Joint Commission on Rural Reconstruction. It was established in 1948 on mainland China then moved to Taiwan. Liang only worked for them for a short time before resigning in order to return to his family, who lived in Hong Kong.

From 1949 to 1956 the Liang family lived in Hong Kong, where Liang worked for the Hong Kong Engineering and Construction Co. LTD. from April 4, 1955 to August 15, 1956. During this time he also held a teaching job. He applied for the Refugee Relief Act of 1953, which at that time was for professional refugees only and required two sponsors. Fortunately, Liang developed many friendships while he was a student at Michigan State and they were more than willing to sponsor him. In September 1956 the Liang family took the President Wilson ocean liner to the United States. They settled in San Francisco, California, and Liang was able to get a job as an engineer. A few months after arriving in America, Liang passed away on April 13, 1957.