Candice Bergen, parliamentary secretary to Public Safety Minister Vic Toews, told the House of Commons the agency is investigating.
The Toronto Sun newspaper reported that an unidentified complainant went to the Public Service Integrity Commission after the Aug. 3 party.
The complaint said five officials from the border agency attended the dinner, along with Chinese embassy officials and agents from China's public security ministry.
The dinner included copious amounts of alcohol, to the point where the complainant compared it to "a frat party."
Bergen said any inappropriate actions would be punished.
"Canadians expect law enforcement officers to act with integrity at all times," she told the Commons.
"CBSA is looking into the facts of this situation. Anyone found to have behaved inappropriately, or acting inappropriately, will face sanctions and discipline."
However, she said no one should jump to conclusions.
"There is due process for this kind of scenario."