Former Health Services Union boss Kathy Jackson has pleaded not guilty to misuse of union funds.

Ms Jackson will stand trial on accusations she passed off personal expenses as work expenses, part of 166 charges she now faces.

Her not guilty plea prevents a committal hearing that was expected to run for two weeks, and waives her right to cross-examine witnesses during the pre-trial stage.

The list of potential witnesses included jailed HSU national secretary Chris Brown, NSW union boss Gerard Hayes and senior officers Peter Mylan, Rob Hull, Barry Gibson, Craig McGregor and Neil Bowker.

Ms Jackson is charged with 18 counts of theft, 147 counts of obtaining financial advantage by deception and one charge of obtaining property by deception.

She is accused of using union credit cards to pay for international flights and luxury hotels, passing off $500,000 worth of personal expenses as union costs.

Ms Jackson will appear before the Victorian county court this week for a directions hearing about a trial date, kicking off a trial expected to run for several months.