In mid-September, the Conservative Party was running 691 adverts classed as active by Facebook, more than any other political party in the UK, the research revealed on Thursday.
In contrast, younger Facebook users were being shown ads by the ruling party on issues such as policing and mental health.
The Conservative adverts criticise opposition leaders for wanting "to ignore our Brexit vote".
Many of the ads are identical, or minor variations on a theme, run multiple times.
They were viewed between half a million and 2.6 million times in total.
A Conservative Party official said many ads were no longer active, even though they appeared to be so.
Facebook has about 40 million users in the UK, the BBC reported.
An organisation running adverts on Facebook can choose the target audience for each ad by gender, age, location, and interests.
Meanwhile, though running far fewer adverts than the Conservatives, the Liberal Democrats were also targeting Brexit messages towards specific age groups, the research revealed.
In direct contrast to the Conservative Party's, the Liberal Democrats' ads were about stopping Brexit and are mostly being seen by people under the age of 45.
The Labour Party was running fewer ads than the Conservatives, with 276 active adverts.
Brexit is one of the issues covered by Labour but as part of a wider mix including fox hunting and the environment.
( With inputs from IANS )