China and Taiwan are about to begin the highest-level talks since the end of the Chinese civil war in 1949.
Wang Yu-chi and Zhang Zhijun, the top cross-strait officials from each side, will meet at the four-day talks in Nanjing.
Taiwanese officials said they would raise press freedom after Beijing denied access to some media outlets.
Beijing is likely to push Taiwan to pass a free trade deal that is currently stalled in parliament.
Speaking to reporters before departing from Taiwan, Mr Wang, head of Taiwan's Mainland Affairs Council, said: "My main aim during this visit to the mainland is to promote mutual understanding between the two sides."
In quotes carried by Taiwan news agency CNA, he added that he hoped the visit, which was "not easy", would go smoothly, and said the two sides would not be signing any agreements during the talks.
China insists that Taiwan is a part of its territory and has a stated aim of reclaiming the island.
Taiwan still calls itself the Republic of China and nominally claims the same territory as the Communist government in Beijing, although it does not press these claims.
The US is committed to defending Taipei, despite not formally recognising Taiwan as an independent country.
The situation has created a decades-long military stand-off between Beijing and Washington.
But cross-strait ties have improved since Taiwan's pro-Beijing President Ma Ying-jeou was elected in 2008.
Cross-strait flights began in 2008, and tourists from the mainland have boosted Taiwan's economy.
Trade agreements have allowed Taiwanese technology firms to expand massively, investing billions of dollars in the mainland.
However, Mr Ma is unpopular and analysts say his governing Kuomintang party is likely to lose local elections later this year.
The talks are the first formal government-to-government dialogue since the 1949 split.
For years, mainland China and Taiwan dealt with each other indirectly, though so-called friendship associations and trade groups, the BBC's Celia Hatton in Beijing reports.
Amid all the smiles, tension remains: China refuses to retract its long-standing threat that it could eventually take back Taiwan, by force if necessary, our correspondent adds.
Taiwan negotiators are likely to propose the posting of permanent representatives on each other's territories.
But they will also face pressure to talk about press freedom after China refused accreditation to several media outlets.
"Press freedom is a universal value," Taiwan's Mainland Affairs Council said in a statement.
"We've repeatedly said that the most important thing regarding news exchange between the two sides is the free and equal flow of information."
Many Taiwanese are sensitive to issues of press freedom, having lived under a dictatorship that tightly controlled the media until the 1980s.
Correspondents say Beijing's negotiators are likely to press for closer economic co-operation.http://www.bbc.co.uk/news/world-asia-china-26129171