Vaillancourt is facing 12 charges, including conspiracy, fraud, influence peddling, breach of trust and gangsterism.
The preliminary hearing involves Vaillancourt and 35 co-accused. It is expected to last eight weeks.
The first four weeks will be devoted to hearing the prosecution's primary witnesses.
A total of 37 people, including Vaillancourt, were arrested in May 2013, in a province-wide operation carried about by Quebec's anti-corruption unit, UPAC.
One of the individuals arrested, Robert Cloutier, has died.
Once known as the "King of Laval," Vaillancourt stepped down in November 2013 amid an investigation by UPAC and allegations of corruption in testimony given at the province's Charbonneau inquiry.
Vaillancourt was mayor of Laval for 23 years.