Both companies' boards have unanimously approved the transaction, which still needs approval from Smithfield's shareholders. The transaction may also be subject to review by the U.S.'s Committee on Foreign Investment, which evaluates the potential national security effects of transactions. The process typically includes a 30-day initial review, followed by a 45-day investigation before making a recommendation to the president.
Chinese investment in the U.S. is still comparatively low but has risen sharply in recent years. China has accused the U.S. of discriminating against its companies, although analysts say American firms face bigger obstructions investing in China.
The companies put the deal's total value at about $7.1 billion, including debt. Smithfield Foods has about 138.8 million outstanding shares, according to FactSet. Smithfield's stock will no longer be publicly traded once the deal closes.
Its shares surged $6.50, or 25 percent, to $32.47 in midday trading Wednesday.
Shuanghui has 13 facilities that produce more than 2.7 million tons of meat per year. Under the agreement, there will be no closures at Smithfield's facilities and locations, including its Smithfield, Va., headquarters in the historic southeastern Virginia town of about 8,100 where it was founded in 1936, the companies said.
Smithfield's existing management team will remain in place and Shuanghui also will honor the collective bargaining agreements with Smithfield workers. The company has about 46,000 employees.
"This transaction preserves the same old Smithfield, only with more opportunities and new markets and new frontiers," Smithfield CEO Larry Pope said in a conference call. "This is not a strategy to import Chinese pork into the United States ... this is exporting America to the world."
"People have this belief ... that everything in America is made in China. Open your refrigerator door, look inside. Nothing in there is made in China because American agriculture is the most competitive and efficient in the world. This is the one place America can absolutely compete," he said.
With China and the U.S. being "the most important markets," Zhijun Yang, managing director of Shuanghui, said in a conference call with investors, "together we can be a global leader in animal protein. ... no other combination has such a great opportunity."
Foreign food, such as milk powder from New Zealand and vegetables from neighboring Asian countries, is prized by Chinese consumers because of frequent domestic food safety scandals.
Among the most notorious, six babies died and 300,000 were sickened in 2008 from drinking infant formula and other dairy tainted with the industrial chemical melamine.
Shuanghui's reputation was battered in 2011 when state broadcaster CCTV revealed its pork contained clenbuterol a banned chemical that makes pork leaner but can be harmful to humans.
In recent months, Continental Grain Co., one of Smithfield's largest shareholders, has been pushing Smithfield to consider splitting itself up, saying it was time for the company to "get serious about creating shareholder value." Following a March letter from Continental Grain, Smithfield said it would review the suggestions "in due course." Representatives from Continental Grain did not immediately comment on the deal announced Wednesday.
In its most recent quarter, in March reported its net income rose more than 3 percent, helped by gains in hog production, its international business and its packaged meats such as deli meats, bacon, sausage, and hot dogs a large growth area for the company.
Still pork producers like Smithfield have been caught in a tug of war with consumers. The company needs to raise prices to offset rising commodity costs, namely the corn it uses for feed. But consumers are still extremely sensitive to price changes in the current economy. By raising prices, Smithfield risks cutting into its sales should consumers cut back or buy cheaper meats, such as chicken.
The Smithfield deal including assumed debt would eclipse a Chinese purchase of a stake in a big U.S. investment firm as well. In December 2007, China Investment Corp. bought a 9.9 percent stake in Morgan Stanley valued at $5.6 billion, according to research firm Dealogic.
AP Business Writer Michelle Chapman in New York contributed to this report.