Former Prime Minister John Key said US Speaker Nancy Pelosi's visit to Taiwan this week was "reckless" and "dangerous".

He told TVNZ's Q+A with Jack Tame the visit was "reckless if you want to be kind, it was provocative, and it was actually dangerous," he said.

"I say that because everyone understands how significant that step is," Key said.

Pelosi arrived in Taiwan this week on a tour of Asia. The visit enraged China, which claims the self-ruling island as its own territory.

"Everyone knows that if the third most significant elected official in the United States turns up on Taiwanese territory, that is poking the bear," Key said.

Key said Pelosi had a "consistent view" on Taiwan, but wanted to make a personal stand.

"She wants to make a personal stand, but at what cost?" he said, noting it increased tensions in Asia and that hundreds of thousands of jobs depended on Taiwan.

Key said he visited Taiwan as a junior backbencher in 2003, but he would no longer visit as a former prime minister.

"I would never have gone as prime minister and I would never have sent a minister," Key said.

Key said the relationship with China had "deteriorated considerably" since his time as prime minister in 2008.

"If I got out as prime minister and talked about China it was seen as talking about jobs and taking the economy out of the GFC," Key said.

Key said what had changed was the presidency of Donald Trump.

"What really changed was Donald Trump - he changed the global narrative on China for his own domestic reasons," Key said.

"He saw trade not as a win-win situation but as a win-lose situation," Key said.

Key said he remained positive on China, and its leader President Xi Jinping.

"I personally like him," Key said.

Key said his philosophy was to build a better relationship with China through trade, which gave New Zealand more leverage.

He did not back China's recent efforts in the Pacific.

"I'd much prefer that they work alongside Australia and New Zealand. I think we could do it a lot better together and achieve better outcomes," Key said.

Key said he believed the Government was "trying" to maintain good relations with China.

His advice to the Government was that New Zealand had both historic relationships with traditional security partners like the Five Eyes countries, but China was the "only country" in the world likely to emerge as a superpower alongside the United States.