Lieutenant-Colonel Yury Bezler has been declared persona non grata and has been given two weeks to depart, after serving less than a year as assistant defense attache at the Russian embassy in Ottawa, said the Ottawa Citizen and others, citing unnamed sources.
The embassy and Canada's foreign affairs department declined to comment.
Bezler's departure comes amid tensions between Russia and the West over its annexation of Crimea and what the United States described earlier as Russian agents stoking a flaring secession crisis in eastern Ukraine.
A Canadian army reservist meanwhile was arrested and charged for stabbing a Russian diplomat last month, after the diplomat was found bleeding in the lobby of his Ottawa apartment.
The diplomat has since left the country, police said.
Canada's foreign minister has said the incident was not believed to have been politically-motivated.