The 27-year-old suffered brain damage, lost both his legs and broke his back when his Land Rover was caught in the blast of a Taliban bomb in 2006.
The Ministry of Defence (MoD) pledges to fund wounded soldiers’ rehabilitation until completion.
But LBdr Parkinson has received a letter from the Army Medical Services Board, saying they are recommending he is medically discharged.
What progress (injured soldiers) have made as a result of military assistance is in danger of being lost or even reversed.
Diane Dernie, Ben Parkinson’s mother
And his mother Diane Dernie told Sky News he had also learned his compensation would be capped at £570,000 – despite the MoD saying it should be in excess of £1m.
“For Ben, the killer is that he sees his future in the Army,” she said.
“He was a soldier since he was 16 and it’s very, very difficult for Ben to move on.”
LBdr Parkinson, who served with 7 Para, Royal Horse Artillery, sustained a total of 37 injuries in the explosion. He has had a gruelling 37-hour-a-week recovery programme involving gym work, speech therapy and physiotherapy.
Ben Parkinson has undergone five years of gruelling rehabilitation
The Para’s injuries included punctured lungs, while both his legs were amputated above the knee.
His mother said: “We understand the Army’s position that they could never have expected the number of seriously injured that they have, but they did make promises that they would be in the Army until their rehab was complete.
“The problem is, who decides when that point is? Ben’s rehab is very far from complete, he’s got a lot more to achieve.
“For Ben it was a double whammy, because two days after he received the news that he was to be medically discharged, he also received news that his compensation was to be capped.
“So he lost the wherewithal to pay for his own rehab and looked as if he was going to have his financed rehab taken away from him. It’s totally unfair to expect the NHS to deal with these kinds of injuries.”
Mrs Dernie said she believed many more soldiers were facing similar difficulties.
“They have been promised that the NHS will look after them but the NHS is simply not equipped to deal with them,” she said.
“What progress they have made as a result of military assistance is in danger of being lost or even reversed.”
The MoD said: “We do not comment on individual cases.
“However, every case is assessed individually and no-one will leave the Army until they have reached a point in their recovery where it is right for them to leave, however long that takes.”