An Adelaide student who is accused of murdering his mother has told a court he fought back in self-defence after she got angry that he was not practising piano.

Key points: Accused man Wei Li said his mother demanded he reach professional pianist standard

Accused man Wei Li said his mother demanded he reach professional pianist standard He said a beating resulted if his school report card was not straight As

He said a beating resulted if his school report card was not straight As Court heard of online searches about stabbing, avoiding police and phone tracking

Wei Li, also known as Daniel, told a jury in Adelaide his mother "just came at me out of nowhere" in March 2011 at the family's Burnside home.

Li, 22, said his mother Emma Mae Tian, 41, yelled and screamed because he did not want to do piano practice.

He said his mother had something in her hand and he was unable to reason with her.

"I think she wanted to kill me, I had to fight back, I had to stop her," he told the court.

The law student said he was unable to remember anything beyond that point.

The court was told previously Ms Tian was attacked with a metal pole, was strangled and suffered more than 50 injuries.

Her body was found days after the attack, wrapped in blood-soaked sheets on a lounge room floor.

Li said he wrapped the body "out of respect" and "nothing after that point was rational".

He told the court his mother had wanted him to reach professional standard on the piano.

"I started playing the piano when I was about three years old," he said.

"My mother very much emphasised my piano training."

Son beaten if report card was not straight As, court told

The former Prince Alfred College student said his mother had never been satisfied with his marks.

"If I don't get a straight A in a school report that would result in a beating," he said.

He spoke of a time when they had been very close.

"Our relationship in the beginning it was good," he said.

"[There was] a very gradual transition … it got so bad that she started beating me on a daily basis."

Li's father was in China on business at the time his wife died and the son bought a flight to Melbourne, then later travelled to China, where authorities located him about three years later.

The court was told Li had used his laptop computer about the time his mother died to find a video about tying knots.

He also did online searches about stabbing, avoiding police and mobile phone tracking.

Li told the court he had thought about suicide since he was 12 and researched ways to die.

"I've been obsessed with suicide for a long time," he said.

The accused man denied he intended to murder his mother as "she meant everything to me".