Warren Lee Pierson, 81, who was a government lawyer, banker, diplomat and board chairman of Trans World Airlines, died Thursday in San Diego, Calif.

Mr. Pierson began his government career in 1933 as special counsel to the Reconstruction Finance Corporation. He then joined the Export-Import Bank as general counsel and served as president of the bank from 1938 to 1945.

During his years at the bank, Mr. Pierson traveled to Europe, China, and Latin America to promote U. S. trade and help U. S. corporations penetrate foreign markets. He gained a reputation as government banker whou could cut through red tape, and who at times would solve a problem by boarding a plane and flying directly to the country where a problem may have existed.

He attended the 1944 Bretton Woods Monetary Conference as a financial adviser to the U. S. delegation. This conference was instrumental in the establishment of the World Bank and the International Monetary Fund. The next year, Mr. Pierson attended the Inter-American Conference in Problems of War and Peace in Mexico City as a U. S. delegate.

After World War II he left government service to become chairman of All America Cables and Radio, a subsidiary of International Telephone and Telegraph Corporation (IT&T), until 1947. He also served on board of directors of IT&T from 1942 to 1972.

Mr. Pierson served as chairman of the board of Trans World Airlines from 1947 through 1961.

While board chairman of TWA, he also served as a U. S. representative to the Tripatite Commission on German Debts. He was appointed to this post in 1951 by President Truman and given the rank of ambassador.

It was the job of the commissions, meeting in London, to negotiate a settlement of pre-World War II German debts owed the United States, the United Kindom and France. The talks concerned the liability of what would eventually be the new Federal Republic of Germany, finally established in 1955, for payments of aid granted by the U. S. under the Dawes and Young Plans as well as post-World War II aid.

In addition to his work in government and private industry, Mr. Pierson served as president of the International Air Transportation Association from 1950 to 1951, and president of the International Chamber of Commerce from 1955 to 1957.

Mr. Pierson was born in Princeton, Minn., and earned a bachelors' degree from theUniversity of California and a law degree from Harvard University.

During World War I he served as an ambulance driver with the French army and then in the U. S. Army field artillery.

He is survived by his wife, Eleanor, of the home in California, and a sister Celia P. Heriot, also of California.