He will give business leaders the message in Glasgow today as the Coalition considers ways of extending HS2 services north of the border.
The UK Government review of how HS2 could benefit Scotland, announced in November and due to report soon, has prompted speculation that, as some MPs believe, the £43bn project should begin "from both ends".
Previously, Vince Cable, the Business Secretary, has suggested that if Scotland became independent, there would be no chance of the project being extended north of the border.
In April, First Minister Alex Salmond denounced the UK Government's high-speed rail plans as "lacking high ambition" and announced a feasibility study on starting the scheme from Scotland.
Last week at a Westminster lunch Mt McLoughlin was asked if independence could kill off any chance of HS2 being extended to Scotland.
After a long pause he replied: "It's very important for HS2 to serve the whole country. We are far better as one rather than trying to split the country up."
He then added: "I want to see HS2 services going to Scotland and I'm working on those proposals at the moment."
Today in a speech, the Transport Secretary will say the Coalition inherited an infrastructuire deficit as well as a fiscal deficit when it came to power in 2010.
"According to the OECD, the UK has consistently invested less in our infrastructure than our major competitors.
"That's why over the next five years as part of our long-term economic plan we will be making a record investment in Britain's railway," Mr McLoughlin will say.
This, the Minister, will explain, is to include the Northern Hub, improving links between Glasgow and Manchester, in addition to running larger, more reliable trains on the East Coast mainline.
He will point out how in the last year alone, the Scottish Government has invested almost £600m in rail infrastructure, including new stations at Haymarket and Dalmarnock and the electrification of the Glasgow to Cumbernauld line.
But the biggest change will be the start of HS2 in three years' time, creating the first north-south railway for a generation.
"By cutting the journey times from Edinburgh and Glasgow to cities in England, HS2 will boost the Scottish economy by around £3bn," the Secretary of State will declare, adding: "Our objective is a national network that will bring the constituent parts of the UK closer together."