The man, who is now 18 years old, is charged with, among other things, murder and attempted murder.
It was in July last year that the man went on the attack in connection with a Taylor Swift-themed dance class in Southport.
Three girls, aged six, seven and nine, died. The man is also charged with attempted murder of another eight children and two adults.
Several other girls, some as young as five, witnessed the incident.
Suspicion: Manufactured deadly poison
A jihadist terror manual was found in the man’s home. He is also accused of having produced a biological toxin in the form of the plant poison ricin.
The knife attack itself, however, has not been classified as a terrorist crime because the motive is still unknown.
The stabbing shook Britain and led to riots in several English cities, fueled in part by rumors that the man was an asylum seeker.
Over 1,200 people were arrested in connection with the riots and hundreds of people have been sentenced to up to nine years in prison, AP writes.
The trial, which is taking place in Liverpool, is expected to last four weeks. The man has so far not made a statement in court.