According to a report in The Daily Mirror, Harmison will "follow his best friend Andrew Flintoff by announcing his retirement from Test cricket after the Ashes."
The 30-year-old, who retired from one-day cricket in 2007, is reportedly tired of the numerous injury breakdowns that have marred his career.
He will, however, continue playing for his county side Durham.
Harmison has 221 Test wickets, making him the 11th highest wicket-taker for England.
However, loss of form and fitness issues have meant that he has been selected for only four of the last 20 Tests played by England.
Harmison is certain to be included in the 13-member team for the third Ashes Test starting July 30 in Edgbaston.
England lead the series 1-0 after having won the second Test at Lord's.