Specialist officers will carry out "intelligence-led" searches as thousands of music fans begin the annual mass exodus from the city to the weekend festival.
Police sniffer dogs are expected to be drafted in to carry out searches at the city bus station today and tomorrow.
Chief Inspector Alan Porte warned music fans against taking any potentially-lethal drugs at the music event.
He said: "Drug dealing is about making money.
"These people will put whatever they can find into these substances to make as much profit as possible.
"Nobody knows what is in these drugs, or the effects they could have on your health, and drug dealers don't care.
"Please don't let them take risks with your life.
As well as "fake" ecstasy pills, officers will also be looking for deadly "legal highs".
Last year, seven deaths in Scotland were linked to fake ecstasy pills, dubbed Green Rolex.
Schoolgirl Regane MacColl, 17, from Clydebank, died in February after apparently taking a red Mortal Kombat tablet at the city's Arches nightclub.
This weekend's operation is aimed at preventing potentially-fatal pills and "legal highs" being circulated at the festival.
Some "fake" ecstasy pills contain a dangerous stimulant known as PMA.
It causes users to suffer extremely high temperatures, hallucinations and convulsions.
Anyone experiencing unusual symptoms should seek immediate medical help.
More than 85,000 revellers heading for T in the Park, at Balado in Kinross, have been warned about drugs.
Mr Porte, area commander for Glasgow city centre, added: "Anyone caught in possession of illicit drugs will be subjected to the full extent of the law."