Sydney Mardi Gras ready to pop the cork

An enormous exploding champagne bottle, giant butterfly puppets and a wedding ceremony with a difference will form some of the key moments in the 2018 Sydney Mardi Gras parade.

Final preparations are underway ahead of Saturday's colourful display, which will celebrate 40 years of Mardi Gras and is expected to attract nearly half a million people along the iconic Oxford Street route.

There will be 12,500 participants on 200 floats, the largest of which will be carrying about 250 people involved in the original 1978 parade and subsequent riot.

Mardi Gras chief executive Terese Casu says the event helps celebrate the hard-fought equality victories, including 2017's successful campaign for same-sex marriage.

"Importantly, Mardi Gras remains a platform for social justice and equality and an incredible citywide celebration of our LGBTQI communities," she told reporters on Friday.

"For many, equality has been a long, hard journey and this year we celebrate."

The First Nations float will lead the parade with a huge Aboriginal flag, followed by the 78ers and then four floats put together by Mardi Gras organisers to revisit its defining moments.

The champagne bottle will be popped when a dinner party-themed float reaches Taylor Square and highlights the iconic costumes and characters of the past four decades.

Creative director Greg Clarke called it a "wonderfully bizarre and theatrical" float.

Sixty butterfly puppets will create a more sombre moment of the procession, designed to remember those who've died of AIDS-related illnesses.

A same-sex couple will also tie the knot during the parade.

Betty Hounslow, 66, will be on the 78ers float and said the group was proud to have played a role in creating such a spectacular tradition.

"It gives us unbridled joy to see what has grown from that small event so many years ago," she said.

With record spectator numbers expected, the evening also requires a significant police operation and more than 1000 officers will be keeping an eye on revellers.

NSW Police Assistant Commissioner Tony Crandell reiterated the force's official apology issued in 2016 for the past behaviour of officers.

"It's important we acknowledge when we get things wrong," Mr Crandell said.

"The NSW Police force got it wrong in 1978. I'm in a position now ... to make certain we don't return to the days of 1978."

There will also be strategically parked vehicles, an intelligence crew, mounted police, the riot squad and sniffer dogs at the after-party, where music legend Cher will perform.

The parade is expected to get underway at 7pm.

Australian Associated Press

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