Earnings after taxation eased to £474m, compared with £478m in the same part of 2011, the company said in a statement.
However, the group's order book grew to £40bn, compared with £39.1bn previously.
In recent years, the group's performance has been hit as military budgets were cut both in Britain and in the United States.
"The outlook for defence spending in the UK has stabilised," BAE Systems said in the earnings release statement.
It added: "In the US, the approval of the Department of Defence Fiscal Year 2012 budget in December 2011 has resulted in less disruption to the award of defence contracts compared with the corresponding period for 2011."
Profits on its electronic systems were down £8m, while its cyber and intelligence system profits were down by £1m.
Meanwhile, its reduced profit of £67m from US platforms and services was offset by a rise of £110m in the UK equivalent.
More From Sky News