The live stadium show of Ben Hur is sure to have massive earnings in ticket sales with actor Russell Crowe joining its 200-strong cast for two Sydney performances.

Crowe, who grabbed an Oscar for his role as Roman commander Maximus in the 2000 epic movie Gladiator, is set to narrate the production about a galley slave who defied the Roman Empire.

"It's not a play. It's not a musical. It's a spectacle. And you know you've got your chariot races, you've got a boat being boarded by female pirates, Pontius Pilate making his decision over Christ's future, so it's gigantic, it's amazing," Crowe said in Sydney on Tuesday.

The $15 million production of the two performances is set at Sydney's ANZ Stadium on October 22 and 23.

The stadium will be converted into a Roman amphitheatre. A full-scale chariot race and sea battle and stages depicting the town of Judea and the Roman Senate will also wow the audience.

According to Executive Producer Andrew Guild, the show's creators were very happy that Crowe joined them.

"When the producers of this particular production suggested that Russell was interested and had shown some interest, they were absolutely - well, what can I say? - they were gobsmacked," Mr Guild told reporters.

It is yet to be determined whether Crowe will narrate the performances live or pre-record them. He says French director Robert Hossein still has to decide on it.

"I've played around with the script. They've given it to me and I've recorded a few versions of it, but I'll be having that conversation with the director when he gets here, and we'll see how we're going to work it out then," Crowe said.

"There's a thousand moving parts or more as you can imagine with something like this, so we'll let him tell me."