Leukaemia had previously been the deadliest cancer for children in the US, though the report shows that the number of child deaths from brain cancer has now outstripped it.
The report said that: "During 1999-2014, brain cancer replaced leukaemia as the most common cancer causing death among children and adolescents aged 1-19 years, accounting for three out of 10 cancer deaths in 2014."
Both of the types of cancer accounted for 54.8% of all child cancer deaths in 2014 compared to 53.4% in 1999. Brain cancer death rates had increased significantly from 23.7% to 29.9% in that time, as leukaemia deaths fell from 29.7% to 24.9%.
Katherine Warren, head of paediatric neuro-oncology at the National Cancer Institute said: "For paediatric brain tumours in particular, we have not made significant headway at all."
She added that it had only recently been understood that childhood brain tumours were "significantly different" to those in adults.
Overall, the picture looked to have improved significantly, with 20% fewer deaths in children as a result of cancer in 2014, compared to 1999.
The cancer death rate in black children in 1999 had been significantly higher than in white children, with 3.01 deaths in every 100,000 black children compared to 2.85 in white children. However, the report said: "No statistically significant differences were observed" between the two groups in the 2014 data.
A disparity between male and female children survival rates continues, with the death rate in female children and adolescents dropping by 22% compared to 18% in male children and adolescents.
The death rate in male children and adolescents had been "continually higher" than for their female counterparts over the same time period.