The numbers of assaults and threats of violence against principals have risen significantly in recent years, according to Australian Catholic University (ACU) research.

Australian principals were seven times more likely than Australians in general to be assaulted, it found.

Burnie High School principal Judy Fahey was sworn at repeatedly and slammed into a wall by furious parent Adrian Barry Evans in November last year, after his son had been suspended.

Evans was sentenced to one month's jail, wholly suspended, on Wednesday for the assault and for later resisting a police officer.

"It is alarming that the number of assaults on principals across Australia has increased by 15 per cent over the last three years," Australian Education Union Tasmanian president Terry Polglase said.

"Every principal has a story, but they never get to say it, though. The culture doesn't allow it and school staff don't want to undermine confidence in the education system."

The ACU found parents were the most likely perpetrators when principals were subjected to bullying.

It found the proportion of principals who had been threatened with violence by parents had grown from 19 per cent in 2011 to 25 per cent in 2014. The proportion of principals who had received violent threats from students grew from 17 per cent to 24 per cent in the same period.