How many members are there in US parliament?

There is no US Parliament.

There are, however, 535 voting Congressmen, plus 5 nonvoting Delegates and the Resident Commissioner of Puerto Rico.

The US Congress is a Bicameral Legislature that lacks the far reaching powers of a Parliament which includes both the Legislative and Executive functions of government. The Executive Branch, led by the President, is an independent and much stronger governmental force in the US system.

There are, 100 Senators, two from each State, that comprise the upper chamber called the Senate. And, apportioned by population, there are 435 in the House of Representatives. In addition, US Territories and the Commonwealth of Puerto Rico are represented by 5 delegates & and one Resident Commissioner (respectively) which can vote in Committees, but not on any issue before the entire House.