The Reagan administration is sending two teams of trade and economic experts to Latin America Monday to enlist countries there in the Caribbean Basin Initiative, a 12-year program designed to revitatilize the sagging economies of the region.

The CBI was signed into law just two weeks ago to promote economic development through trade concessions and special tax advantages. The quick start appears to be part of a deliberate effort by President Reagan to show that American interests in Latin America are humanitarian as well as military--a point he made twice during speeches to Hispanic groups last weekend.

The CBI covers 27 Latin American and Caribbean nations--including left-leaning Guyana, Grenada and Surinam, but not Cuba. Countries must comply with conditions set by Congress and the administration in order to reap its benefits. Among these conditions is an automatic ban on any Communist country.

The Sandinista government of Nicaragua, which has been under attack by the Reagan administration for its close ties to Cuba and its support for antigovernment guerrillas in El Salvador, can qualify for CBI benefits, although it is unlikly to gain any. Nonetheless, representatives of the State Department and the Office of the United States Trade Representative will visit Nicaragua early in the tour, possibly to show that all nations of the region could take part in the CBI if they meet the U.S. criteria.

Guyana, Grenada and Surinam, who are seen as unlikely even to want to participate in the CBI, will be included in the second round of visits, probably in October.

"Our CBI is designed to bring the power of private enterprise--America's most potent weapon--to help build Latin America and the Caribbean," President Reagan said in a speech in Tampa last weekend.

This is not the first time the United States has tried economic programs to hold back communist inroads into Latin America. John F. Kennedy inaugurated the Alliance for Progress when he took office to counter the influence of Castro's Cuba, and Secretary of State Henry A. Kissinger said after a 1976 six-nation South of the Border tour that expanded trade with Latin nations should be "a central mission and purpose of the inter-American system."

On the same trip, Kissinger--who now heads President Reagan's Latin American task force--delivered a strong warning against foreign intervention in the Western Hemisphere--a key element of the Reagan administration's campaign against what it sees as Soviet-sponsored Cuban aid to Sandinistas in Nicaragua and antigovernment guerrillas in El Salvador.

The administration hopes to qualify the first group of countries for the CBI by November, although special tariff benefits may not take effect for any nation until January because of what was described as problems in the U.S. Customs Bureau.

American officials believe that Costa Rica and Honduras, whose territory is being used by anti-Sandinista guerrillas fighting the pro-Cuban government of Nicaragua, are likely to be among the first countries to qualify for CBI benefits.

So is Jamaica, whose economic achievments through free enterprise since conservative Edward Seaga defeated the social democrat Michael Manley in 1980 elections, was cited by President Reagan in a speech in Tampa last Friday. Other countries considered likely to pass muster for early acceptence are Barabados, the Dominican Republic, and the Eastern Caribbean island nations of Antigua and Barbuda, Saint Lucia, Saint Vincent and the Grenadines, Montserrat and Saint Christopher-Nevis.

The first qualifiers, however, are unlikely to include El Salvador, the focus of American military aid in Latin America, or Guate administration's strong anti-Communist stance in the region. Both nations face problems because of their poood record in human rights is one of the conditions for participating in the CBI, administration sources said.

The CBI, passed over great opposition from organized labor, allows the president to give duty-free status to a large number of goods imported from eligible nations, although textiles--a prime manufacturing product of Third World nations--specifically are excluded.

The law also allows American citizens to take tax deductions for conventions in eligible Caribbean and Latin nations as if the meetings had been held in the United States. The government expects to lose about $5 billion in tax revenue each year as a result of that provision. Last year, Congress passed a $350 million aid program as part of the CBI, but it took heavy lobbying by the administration this year to win congressional approval of its trade provisions.

The criteria for qualifying cover a broad range of policies, including adherence to international trade laws, fair treatement of U.S. citizens' claims arising from expropriation or nationalization of property and a positive human rights record.

Some countries are considered unlikely to qualify because of their refusal to cooperate with American efforts to catch tax cheats. These include countries that have set up banking systems regarded as tax havens, such as the Bahamas, Cayman Island and the Netherlands Antilles.

One U.S. team going out Monday, led by Jon Rosenbaum of the Office of the U.S. Trade Representative and State Department aide Robert Ryan, will visit the Spanish-speaking Caribbean and Latin American nations. The second delegation, headed by USTR official Bennett Marsh and Gerald Rosen of the State Department, will go to the English-speaking countries.