The two factories have so far produced 105,250 sleepers and 148 T-beams, key materials used in the construction of the railway.
Each factory has the capacity to produce 1.5 beams a day each weighing 120 tonnes and 1,000 sleepers a day.
The two factories have employed over 1,000 workers each who have been trained on production of the railway building materials.
The factories will continue operating even after completion of the Mombasa-Nairobi track and will be used to manufacture railway consumables.
“Since last December when the SGR project officially started, we have made a lot of progress and we are on course to complete it on time,” said Julius Li, CRBC manager for external relations and cooperation.
The first part of the railway to Nairobi, estimated at 471km, is set for completion in 2017.
Kenya Railways managing director Atanas Maina said Kenyans working on the SGR will play a critical role in the running and management of the new line upon completion.
Mr Maina said the workers will help reduce reliance on expatriate labour in the next phases of the railway construction.
Kenya has previously said the new railway will cut freight costs to 8 US cents a metric tonne (1.1 tonnes) per kilometre from 20 cents now.
CRBC was awarded the contract in 2011 after signing a deal in which the Chinese contractor promised to assist in facilitating a government to government deal supported by concessional loans from the China Exim Bank.
MPs had raised concerns over the single sourcing and questioned the capacity of the company to undertake the massive project.
Mr Maina said the contractor will remain on site for another year to work on emerging defects within the corridor.