Two Sydney men have allegedly gone to drastic lengths to sneak illegal drugs into Stereosonic by trying to hide them around the venue days before the dance music festival.

Police have been called to Sydney Olympic Park twice in the past week to find individuals attempting to drill holes in buildings and stash dozens of ecstasy pills before the site goes into "lockdown" this week.

Saturday is expected to be one of the biggest days at Sydney Olympic Park since the 2000 Olympics, with 150,000 people attending four events - the Aus-X Open, the Short Course Swimming Championships, the Taylor Swift concert and Stereosonic, a one-day music festival featuring international DJs and electronic acts.

Zane Raffie, 21, was observed last Friday night allegedly trying to drill a hole into a building in the park complex to stash drugs.

Inspector Chris Laid, of Flemington local area command, didn't want to give away further details of Mr Raffie's alleged plot, except to say he was trying to "install something [in the building] that could conceal drugs".

When he was confronted by security guards, he fled the area and police were called.

Investigators later attended his home in Green Valley and seized 10 MDMA pills. He was also allegedly in possession of a "prohibited plant".

On Tuesday night, police were again called to Sydney Olympic Park after security guards observed Ali Ghoneim, 22, acting "suspiciously" in the area.

Police searched his car and allegedly found 95 ecstasy tablets.

They will allege that Mr Ghoneim was trying to hide the drugs around the venue before special event fencing goes up this week and the precinct becomes flooded with event workers and security.

Inspector Laird said police found young festival-goers doing the same thing last year, so they stepped up their surveillance of the area ahead of this year's festival.

"They're going to desperate lengths," he said.

"We know this happens so we've been regularly sweeping the area with drugs dogs over the last few days to make sure we find stuff before the park is fully locked down.

"At the end of the day, if you're planning to take drugs in, you'll get caught. If you've already secreted drugs, we've already found them so don't bother turning up."

Mr Raffie was issued with a Future Court Attendance Notice to appear in Burwood Local Court on February 2 for the charges of malicious damage, trespass and possessing a prohibited plant.

Mr Ghoneim was issued with a Future Court Attendance Notice to appear in Burwood Local Court on December 15 for the charge of drug supply.

As part of their strict conditional bail, both men have been barred from Sydney Olympic Park.

Police said they will be arrested if they turn up for Stereosonic.