President Donald Trump has signed a series of executive orders, including on tax simplification, aimed at reviving the economy and bring jobs back to the US, fast tracking the implementation of his election promises before the first 100 days in office.

Key among the three executive orders was a six-month review of certain provisions of the Dodd-Frank law, a measure passed by predecessor Barack Obama in the wake of the 2008 global financial crisis which Wall Street believed had made their job difficult.

Trump walked down street across the White House to the Treasury Department to sign the executive orders which he said is part of his effort to revive the American economy and bring jobs back to the US.

"We re now in the process of rebuilding America, and there s a new optimism sweeping across our country like people have not seen in many, many decades. We re here today to continue this great economic revival," he said as he signed three presidential directives to further protect American workers and taxpayers.

The first executive action instructs the Treasury Secretary Steven Mnuchin to begin the process of tax simplification.

"Such a big thing. People can t do their returns. They have no idea what they re doing. They re too complicated," he said.

"This regulatory reduction is the first step toward a tax reform that reduces rates, provides relief to our middle class, and lowers our business tax, which is one of the highest in the world and has stopped us from so much wealth and productivity, he added.

In the other two executive orders, Trump instructed Treasury Secretary Mnuchin to review the damaging Dodd-Frank regulations that failed to hold Wall Street firms accountable.

"I mean, they've done really, in many cases, the opposite of what they were supposed to. These regulations enshrine 'too big to fail' and encourage risky behaviour, he said.

"We're taking steps to make our economy more fair and prosperous for all. As part of our broader financial strategy, we're working to open up lending to small businesses and entrepreneurs, including our incredible women entrepreneurs who are doing better and better and better. We want opportunity for everyone and in every single part of our country," Trump said.

Earlier, Mnuchin said under the previous administration, the tax code became extremely expensive and burdensome.

"Individuals and business spend over 6.1 billion hours; the cost is over $230 billion. I think everybody would agree that the tax system is way too complicated and burdensome, he said.