The sentencing would be pronounced on February 25 after arguments on the quantum of punishment by the Special Court that accepted the theory of conspiracy behind the burning of the coach of Sabarmati Express carrying kar sevaks returning from Ayodhya.
The court acquitted prime accused Maulana Umarji while other prominent accused Haji Billa and Rajjak Kurkur were convicted.
"Special Court judge P R Patel has convicted 31 accused while acquitting 63 others," Public Prosecutor J M Panchal said after the verdict inside the Sabarmati jail.
"On February 25, there will be a hearing on the point of sentence, and after that quantum of punishment will be pronounced," Panchal said.
"The conspiracy theory has been accepted by the court," he said.
Scientific evidence, statement of witnesses, circumstantial and documentary evidence placed on record formed the basis of the judgement.
The trial conducted inside the Sabarmati Central Jail here began in June 2009 with the framing of charges against 94 accused in the carnage, that had triggered widespread communal riots in Gujarat.
The accused have been charged with criminal conspiracy and murder in burning of the S-6 coach of the train on February 27, 2002 near Godhra, about 125 km from here in which 59 people were killed.