National will reduce primary class sizes if it comes into power in 2020, leader Simon Bridges says.

The announcement to lift the number of primary school teachers in New Zealand - an issue which once badly damaged National - was the centrepiece of Bridges' speech at his party's annual conference this afternoon.

"All our kids should get the individual attention they deserve," Bridges told an audience of about 600 party members at Skycity Conference Centre in Auckland.

"That's why I want more teachers in our primary schools, to ensure smaller class sizes for our children.

"Schools currently get one teacher for every 29 nine and ten year olds. It's lower than that for younger children.

"Those ratios should be reduced."

The call on class ratios comes six years after National was forced into a humiliating backdown on class sizes when it was in Government.

Bridges' choice of the policy to headline his first conference speech as leader is similar to that of former Labour leader David Cunliffe, who promised to limit classes to 26 students at the Labour annual conference in 2014.

"More teachers means more attention for our kids at a stage of life when they need it most," Bridges told National members today.

"To achieve their potential and reach their dreams our kids need less Facebook and more face time with teachers."

National was committing to attracting more teachers and ensuring they were highly respected, Bridges said. That included looking at their pay, he said. The policy would be developed over the next two years, and did not include a specific figure of what class sizes could be reduced to.

Bridges also said National wanted to improve the quality of early childhood education.

"Most centres do a good job of looking after our young children, but a few not doing good enough is a few too many in my book.

"We need to know what is happening in every early childhood centre in the country."

National would demand the highest standards from ECE centres, he said.

"Or frankly the centre should close its doors."

Asked afterwards why he chose an old Labour policy for his first conference as leader, Bridges said Labour had "talked a big game" on reducing class sizes but never implemented the policy.

Bridges was introduced at the conference by a video in which he played drums, spoke about his family, and admitted to "falling in love with a leftie" - his wife Natalie.

Natalie joined Bridges onstage, as did his three children Emlyn, Harry, and new baby Jemima.

Former National Prime Minister Sir John Key was also watching on.

Sir John, who has kept out of the media to avoid overshadowing National's new leader, said Bridges had not asked him to appear at the conference or to endorse him. He was there because he was a National supporter "until the day that I die", he said.

Bridges' speech had an Australasian focus. The previous National-led Government had reversed the number of people leaving New Zealand for Australia, he said, but that trend was at risk.

"Other countries want what we have, and we can't afford three years lost to working groups and inquiries and uncertainty. We certainly can't afford six.

"Under this Government, business confidence is already at its lowest level since the Global Financial Crisis – while in Australia it's the highest it has been in 20 years.

"We can't let Australia beat us."

The other key theme was that National would be ready for power - unlike the Labour-led Government, he said.

"We'll have the best ideas on the environment, how we can clean up our waterways and protect our beautiful country for our grandchildren.

"We'll have the best ideas for supporting the most vulnerable, to help them turn their lives around.

"We'll have the best ideas on law and order, on how to keep you safer by keeping our most violent predators locked up.

"We'll have the best ideas on health, on education, on housing, and on infrastructure.

"And we'll have the best ideas on the economy, because frankly, that's an area where the Government has no idea at all."