It is understood the move is due to falling sales of diesel-powered vehicles.
The company says it will have no impact on JLR's factory on Wolverhampton's i54 site, where 1,800 people are employed producing diesel and petrol engines.
The former Spitfire factory at Castle Bromwich is the traditional Jaguar factory, employing around 3,200 people making the XF, XJ and XE saloons and the F-Type sports car. But the best-selling new F-Pace and E-Pace crossover models are made at nearby Solihull – JLR's biggest factory with 10,000 staff.
A Jaguar Land Rover spokesperson said: "As is standard business practice, Jaguar Land Rover regularly reviews its production schedules to ensure market demand is balanced globally.
"In light of the continuing headwinds impacting the car industry, we are making some temporary adjustments to our production schedules at Castle Bromwich.
"We are however continuing to over-proportionally invest in new products and technologies, and are committed to our UK plants in which we have invested more than £4bn since 2010 to future proof manufacturing technologies to deliver new models."
The cut to the working week comes in the wake of moves earlier this year to axe 1,000 agency jobs at the Solihull factory.
Just a week ago Jaguar Land Rover boss Ralf Speth had blamed that decision on the was diesels had been 'demonized'.
He also warned that a 'hard' Brexit could cost tens of thousands of jobs at JLR and its supplier companies in the UK.
Today the Castle Bromwich plant's local MP, Jack Dromey, said: “Brexit chaos and the Government’s mishandling of the transition from diesel pose a growing threat to the future of the historic Castle Bromwich Jaguar plant.
"The plant has already lost the best part of 1,000 jobs and will now be going onto a three-day week until Christmas to avoid further job losses.
“Brexit now threatens the jewel in the crown of British manufacturing excellence. Ministers must get it right or the future is bleak.
“This morning, a wide-eyed Brexiteer Bernard Jenkins MP, in his ideological zeal accused Jaguar Land Rover chief executive Ralf Speth of ‘making it up’. Now we know fears are justified. A hard Brexit or no deal will be catastrophic for Britain’s automotive industry.”
And Unite assistant general secretary Tony Burke said: “Today’s announcement from Jaguar Land Rover regarding Castle Bromwich follows on the warning last week from JLR CEO Ralf Speth about the future of JLR in the UK in the event of a ‘hard Brexit’ and a bad Brexit deal.
“This is the continuing effect of the chaotic mismanagement of the Brexit negotiations by the government which has created uncertainty across the UK’s automotive industry and the manufacturing sector generally.
“It is also the result of the mishandling of how the UK makes a just transition from diesel and combustion engines to electric vehicles. Both issues have damaged the ‘jewel in the crown’ of UK manufacturing – our automotive industry."
The latest move comes after a tough few months for Jaguar Land Rover, with sales falling in the UK, Europe and in its key Chinese market. The UK and European falls have been blamed partly on issues with diesels, particularly in the wake of the Volkswagen emissions scandal.
The axing of the 1,000 agency workers at Solihull in April also saw 360 workers transferred to Solihull from Castle Bromwich.
JLR had already slowed the production line at Castle Bromwich earlier in the year, and temporarily cut the number of shifts at its Halewood site on Merseyside – which makes the Range Rover Evoque – from three to two.
The company is also moving production of its iconic Land Rover Discovery from Solihull, after 30 years, to a newly completed factory in Slovakia.
JLR says this is to make room for major investment and reorganisation of its Solihull factory. It has also confirmed it will build the next-generation Evoque at Halewood.