The company said the agreement included a guarantee that a conductor would be retained as the second member of staff on board new trains being rolled out next year.
The dispute led to several days of strikes on the rail network over the summer but further planned industrial action was suspended earlier this month to allow for further talks.
ScotRail said the RMT would now present the proposal to its members in a company-wide vote.
The company said discussions had also taken place with Aslef, the train drivers’ union, and a similar in-principle agreement reached.
ScotRail Alliance managing director Phil Verster said: “I am pleased that we have reached an in-principle agreement with the RMT and Aslef unions that, if formally agreed, will bring this dispute to an end.
“This will end the uncertainty for our people and our customers, and will allow us to concentrate on delivering the best possible service for Scotland, every single day.
“What we have put forward in our proposal will make our service more efficient and more effective while maintaining and enhancing the service we provide to our customers.
“It means that the new faster, longer, greener trains that will arrive in autumn next year really will be a revolution in how we deliver our service.”
An RMT spokesman said: “After long hard hours at the negotiating table, and a sustained period of determined and solid industrial action involving our members, RMT’s team will be reporting back to the unions executive tomorrow where the details will be considered in full.
“A further statement will be issued by the union after that executive meeting.”
In August the long-running dispute was suspended following six weeks of disruption to passengers.
In a statement in August, RMT General Secretary Mick Cash said: “The union has made sufficient progress to enable us to suspend the current programme of industrial action on ScotRail to allow for further detailed discussions on the issue of platform train despatch procedures.
“The progress we have been able to make in this dispute is entirely down to the resilience, determination and strength of our ScotRail members who have taken wave after wave of rock-solid action in defence of rail safety. They are a credit to the entire trade union movement.”
ScotRail have said a solution to the dispute is “in talks not strikes”.
Phil Verster, Managing Director of the ScotRail Alliance said: “I am really pleased for our customers and our people that the RMT have accepted our request to suspend further industrial action.