This includes physical, sexual and emotional abuse, neglect and exposure to domestic violence, the Australian Child Maltreatment Study (ACMS) found.

Australian Catholic University's Institute of Child Protection Studies Professor Daryl Higgins told ACM that experiencing a single type of abuse in childhood was an atypical experience.

Children were more likely to experience nothing or multiple types, he said.

The study of 8,500 Australians over 16 years old found that children targeted by multiple types of maltreatment were the largest demographic at 39.4 per cent.

Young people targeted by a single type of maltreatment were the smallest demographic at 22.8 per cent and children suffering no abuse or neglect made up 37.8 per cent of respondents.

Gender plays a part. The research showed girls were at greater risk, with 43.2 per cent of female respondents confirming they experienced multi-type maltreatment, while 34.9 per cent of boys reported the same.

"I developed the concept of multi-type maltreatment almost 30 years ago," Professor Higgins, the ACMS chief investigator said.

"I knew that experiences of maltreatment-overlap were common, but we've never had such rigorous and comprehensive data to show how common is it," he said.

Queensland University of Technology School of Law Professor Ben Mathews said the study was the first to identify how common five forms of child maltreatment (physical, emotional, and sexual abuse, neglect and exposure to domestic violence) are around Australia.

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"That's quite a unique feature, few studies have done that," ACU Professor Higgins said.

"They tend to look individually at different types - and this disguises the reality that many children are exposed to multiple harms," he said.

This abuse has implications for mental health disorders and health risk behaviours later in the life of these children, QUT's Professor Mathews said.

"A major area of concern is the increase in sexual abuse by known adolescents, the group who inflict the greatest proportion of all sexual abuse," he said.

He said the research indicates "historic social shifts", with sexual abuse in some groups declining in response to changing culture and laws.

"We need to ensure these continue," he said.

"Similarly, we found a significant recent decline in physical abuse, indicating the success of prevention programs, parenting education, and social norms supporting children's rights," Professor Mathews said.

Support is available for those who may be distressed. Phone Lifeline 13 11 14; Men's Referral Service 1300 776 491; Kids Helpline 1800 551 800; beyondblue 1300 224 636; 1800-RESPECT 1800 737 732.