Zeng Hanlin, 66, fled China in 2004 to escape the charges but was deported in March last year after Canadian authorities dismissed concerns he could be tortured or executed if he returned to China.
He was tried and convicted of fraud in November over a stock scheme linked to a failed business merger and a court in the southwestern city of Chengdu in February sentenced him to 15 years in prison.
Canadian rights lawyer David Matas said the family has written to Canadian Prime Minister Stephen Harper to ask him to "express concern" about Zeng's prosecution to Chinese authorities, and is now pressing its case in federal court.
In its letters to Harper, obtained by AFP, the family said the first legal proceedings did not meet "basic standards of due process or human rights."
Zeng had been denied contact with his family, medication for diabetes, and proper legal counsel, they said.
Canada bans the return of prisoners to countries where they might face torture, or unfair prosecution.
"All we want is for the Canadian government to say it is concerned about the criminal proceedings against him (Zeng), and that it is expressing that concern to the government of China," Matas told AFP.
"The hope is that Ottawa's involvement would impact on his appeal, either resulting in a withdrawal of the prosecution or a ruling at the appeal's court that the trial was unfair," he said.
Zeng lodged an appeal against his sentence last month, while his family maintains that he is "innocent" of the charges and wants the case to be heard in an open court in Beijing to ensure a fair trial.