Cao Tianqin (Chinese: 曹天钦; 5 December 1920 – 8 January 1995), also known as Tien-chin Tsao, was a Chinese biochemist and a professor at the Shanghai Institute of Biochemistry. With a research focus on muscle protein, he discovered the myosin light chain and pioneered the study of tropomyosin and paramyosin using electron microscopes. He was a strong advocate and main leader for the synthesis of insulin, and spearheaded the research of plant viruses in China.