The deal marks the latest initiative in China's keen pursuit of overseas high-speed rail deals.
Analysts say the project could open up the underdeveloped US high-speed rail market.
There are about a dozen high-speed rail projects in the US, but they have struggled to gain traction.
Private rail venture XpressWest will form a joint venture with China Railway International USA.
The firm is owned by a consortium made up of subsidiaries from state firms China Railway Group, CRRC, China State Construction Engineering Corporation and China Railway Signal & Communication Corporation.
Guotai Junan analyst Gary Wong estimated the XpressWest project was worth $5bn.
He said the deal would offer little financial benefit to China Railway International USA, but could help give the firm a foothold in the US high-speed rail market.
"If this opens up the United States market for them, opportunities for future expansion will increase. And if [their technology] is used in the United States, it will be easier for them to sell to other countries," he said.
A consortium of Chinese rail firms has teamed up with private US company XpressWest to build a high-speed rail line between Las Vegas and Los Angeles.