The in-house system, known as MT@EC, will be more familiar with EU jargon than online translation services such as Google Translate and will be faster and more efficient than the Commission's existing systems, EU officials said.
The European Commission may have to lay off 10% of its 2,500 translators in the next five years under a new long-term budget agreed by member states this month.
With the avalanche of documentation produced by the European Union's complex bureaucracy showing no sign of abating, the Commission's translators could be snowed under unless it can find new ways to speed up their work.
The new system operates using statistical algorithms and is less costly to maintain than an earlier EU machine translation system as it requires fewer specialised staff, project manager Spyridon Pilos said.
"We have one of the biggest collections of human translations," Pilos said. "We want to use this material to teach the machine to translate in terms of the style and terminology we want."
The service is also designed to be more secure than free translation engines open to the public.
Around a quarter of text in EU documents that need translating tends to be previously translated material, said Commission spokesman Dennis Abbott.
Commission translators preparing to decipher a document will see some text highlighted in green and yellow, indicating it has been recognised from memory.
Phrases that are not recognised would still be translated manually, or with the help of the machine translation, which provides a rough version to be edited by a human.
"I could do the work that I do without (machine translation), but I just like working with it," said Commission translator Ann Barnett, who translates French, Italian and Greek into English. "I like having something that I can pull apart and put together again."
Development of a rule-based machine translation system started in the 1970s, and Abbott said the Commission started using machine translation intensively in the 1990s. EU institutions and national governments used this system until 2010, when it became outdated and was phased out.
The project is budgeted at €4.3 million over three years, but Pilos said the cost benefits of MT@EC were difficult to estimate for now.
Commission translators have been using an early version of the system since July 2011. A more polished service will be available for all Commission staff members in July, and it will be used eventually by other EU institutions and member states.