Negotiations on Britain's future relationship with the European Union should be concluded by the time it leaves the bloc in March 2019, David Davis said.
The Brexit Secretary said it would be unwise for talks to drag on into the proposed transition period.
He also indicated the UK is prepared for a clash with the EU over plans to strike trade deals around the world after Brexit.
Giving evidence to the Commons Exiting the EU Committee, Mr Davis said it would be a mistake to allow negotiations to carry on into the proposed transition period following Brexit.
"It would be unwise to get sucked into a negotiation during the transition period itself which is substantive, major," he said.
"Why? Because the balance of power in the negotiation alters. The aim then on the part of the commission would be to spin out the negotiation."
The Brexit Secretary said he was relaxed about the transition period and indicated it could last as long as 27 months.
But he said he expected a clash over whether the UK will be able to seek its own trade deals during the transition period because "there are people within the union who want to restrict any advantage for us".
He insisted that the transition period was not a deferral of Brexit, even though the UK will follow Brussels' rules.
"Firstly we will not be members of the union, we will be replicating to a very large extent the operations of the single market and customs union in order to make sure there is a single change, from the point of view of businesses in particular," he said.
"We will not be subject to the duty of sincere co-operation, which is what stops us arriving at trade deals now, negotiating and signing trade deals now, so that freedom will exist."
But he added: "There may be an argument over the issue of doing outside negotiations, there may well be an argument over that."