Beijing is criticising what it calls "negative content" about China in legislation before the US Congress, saying it would further damage relations already roiled by disputes over trade and technology.
Foreign ministry spokesman Geng Shuang on Friday said cooperation in important areas would be disrupted if the draft National Defense Authorisation Act passes.
The bill blocks transfer of sensitive technology to China and prevents Chinese state companies from receiving US federal funds.
Geng's comments came a day before President Donald Trump is to meet his Chinese counterpart, Xi Jinping, at the G-20 summit in Osaka, Japan, amid hopes the leaders will call a truce in the ongoing disputes.
Geng said the two sides are in close communication over preparations for the meeting with the goal of achieving a "positive result.