BEIJING—The U.S. and China reached an agreement to drop tariffs on a wide range of technology products, in a deal that its backers say could cover $1 trillion in trade and that marks a significant accomplishment amid strained ties between Beijing and Washington.

The two countries late Monday reached a deal to expand the Information Technology Agreement, a global technology trade pact, to cover semiconductors, medical devices, Global Positioning System devices and other newer products, U.S. Trade Representative Michael Froman...