Civil servants were made to watch a 30-minute video called The Espionage case of Tong Daning Stealing Secrets which showed the defendant standing trial, sources told the Reuters news agency.
Tong - an official in the National Development and Reform Commission - was executed in April for selling classified documents for about $250,000, the sources said on condition of anonymity.
The commission Tong worked for is responsible for economic planning and reform and does not deal directly with issues related to Taiwan.
The video showed the defendant standing trial before getting into a police car on his way to the execution ground - but it did not show his death.
Several official websites - such as the Henan Daily, the Hunan weather bureau, Guangxi University and the state-owned China Nuclear Engineering and Construction Corporation - said civil servants had watched the video. They did not give details of Tong's case or the video's content.
China's policy-making Taiwan Affairs Office and Taiwan's Mainland Affairs Council had no immediate comment.
Relations between China and Taiwan have been tense since they split at the end of the Chinese civil war in 1949 but trade and tourism have increased significantly since the late 1980s.
China claims Taiwan - also known as Chinese Taipei - as its own and has vowed to attack the self-ruled democratic island if it formally declares statehood.
Tong is not the only person found to have been spying on China.
A second source said: "There have been several cases of leaking state secrets in the past year."
In 1999, a Chinese major-general and a senior colonel were executed for selling state secrets to Taiwan for $1.6 million in the biggest espionage scandal of the Communist era.
Earlier this year, Chen Hui, who had access to state secrets when he was working for a government think-tank, was jailed for 13 years for selling state secrets to Japan, sources have said.