Eang Vuthy, a project manager for Bridges Across Borders, says the families have not received enough compensation to relocate.
Cambodian officials say they expect Hun Sen to sign even more deals with China on this visit.
China has made great economic strides since the collapse of the Soviet Union, posting double-digit growth.
Some of the bridge survivors say they do not want to see the bridge reopened so soon—if ever.
Ninety-five political leaders from 44 Asia and Pacific nations met in Phnom Penh on Thursday to strengthen their role in the region.
The 2011 budget that the Cambodian National Assembly recently passed totaled to $2.4 billion.
Cambodia has an estimated 25 different mineral types, from bauxite to zinc, gold, iron, and gems.
Thailand is the world's largest rice exporter, followed by Vietnam, and Cambodia meanwhile exports about 100,000 tons per year.
The leaders of Burma, Cambodia, Laos and Vietnam met in Phnom Penh on Tuesday, vowing closer ties for economic growth.
Agriculture has emerged as a main economic driver for Cambodia, propping up the country in the wake of the 2008 financial crisis.
More than 300 participants gathered Wednesday for a national forum sponsored by the International Finance Corporation.