The man accused of murdering his daughter by throwing her off Melbourne's West Gate Bridge will argue he was mentally impaired at the time.

Freeman's Lawyer George Georgiou told the Victorian Supreme Court on Thursday the central issue at Arthur Phillip Freeman's trial would be mental impairment.

Freeman is accused of murdering his four-year-old daughter Darcey Freeman on January 29 this year.

He sat expressionless throughout Thursday's brief hearing before Justice Paul Coghlan, only nodding when Justice Coghlan told him he would stand trial in April next year.

The court heard there was a list of 81 people who may give evidence at the trial.

The trial is expected to begin on April 19 and run for three weeks.