One in eight children over five has a mental health disorder.
The figures come from an NHS survey of 9,117 kids - the first official figures since 2004. It shows how common mental health problems are among children and young people.
The report shows an increase in conditions in the last 10 years, with boys more likely to struggle with their mental health before they're 11.
Between the ages of 11 and 16 both boys and girls are equally likely to struggle with their mental health.
As children get older they spend more time on social media and have more concerns about body image.
The Children's Commissioner for England says there are improvements in mental health care, for example 80% of children with eating disorders are treated within four weeks.
However only around a third of the 338,000 children referred for mental health reasons received treatment within a year.
37% of children were not accepted into treatment or were discharged after an assessment, and a further 32% were still on waiting lists at the end of the year.
This could be because their condition was not judged to be bad enough to need NHS help and could be dealt with at school or by charities.
But the Children's Commissioner for England Anne Longfield says she is concerned children are getting turned away because services simply did not have time to see them.
Mental Health services for adults receive 15 times more money, despite children representing 20% of the population.
Anne Longfield says an extra £1.7bn needs to be invested to bring children's services level with adults.
She say this could help pay for more early help by funding NHS counsellors in schools for example.
Emma Thomas, chief executive of Young Minds, a children's mental health charity, says there isn't enough support for children.
She said the charity gets "calls every day" about children who are waiting for help.
She believes early help in school and more money for children's mental health is needed.
Both NHS England and the Department of Health and Social Care say they have made improving children's mental health care a priority.
Prime Minister, Theresa May says treatment of people with mental illness is one of the "burning injustices" of British society that she wants to tackle as prime minister.
Last month, in his Budget, the Chancellor Phillip Hammond said 10% of the NHS budget would go to help with mental health services.
A spokesman for NHS England said services were improving and in the coming years another 70,000 children will be able to access support.
If you're worried about how you're feeling, tell someone like a parent or a teacher so you can get the help and support that you need.