President Hu Jintao arrived at Phnom Penh on Friday to strengthen ties between the nations, just days before Cambodia hosts a regional summit.
It is the first state visit paid by a Chinese head of state to Cambodia in the last 12 years.
In a written speech delivered upon his arrival, Hu said that China and Cambodia are traditional neighbors of friendship, stressing that "the good-neighborly ties of friendship between the two countries are forged and carefully nurtured by the older generations of leaders", and "have withstood the test of time and international vicissitudes and moved forward steadily".
According to his schedule, Hu will meet Cambodia King Norodom Sihamoni, President Chea Sim of the Senate, President Heng Samrin of the National Assembly and Prime Minister Hun Sen.
After recently attending a nuclear security summit in Seoul and a gathering of emerging economies in New Delhi, Hu is expected to sign a number of cooperation agreements with Cambodia before leaving on Monday.
China is Cambodia's biggest foreign investor, with hundreds of Chinese companies pumping billions of dollars into the nation in recent years for key infrastructure projects such as hydropower dams and coal power plants.
Cambodia is the host country for the Association of Southeast Asian Nations in 2012.
In a written interview with China Daily, Cambodia ambassador to China Khek M Cai Mealy said that "Cambodia, as a chair country for the ASEAN meetings, will help coordinate ties between China and other ASEAN countries".
The ambassador also urged involved ASEAN countries to not let the South China Sea issue affect bilateral ties.
China, Vietnam, Brunei, the Philippines and Malaysia all hold claims to some of the South China Sea and its islands.
China prefers to negotiate with individual countries and not internationalize the disputes. But some ASEAN countries want a collective voice in the negotiations.
Milton Osborne, a Cambodia expert and visiting fellow at the Lowy Institute in Australia, said suggestions that China would exert pressure over the South China Sea issue were just speculation, but that Cambodia would want to avoid any acrimony on its watch.
"Cambodia is in a privileged position in its dealings with China, and I don't think it is going to abandon that position," Reuters quoted Milton as saying.
Upon arriving at Phnom Penh, Hu immediately had a telephone conversation with King Norodom Sihanoak's wife, and thanked her for the efforts in nurturing the bilateral relationship.
Phnom Penh gave a warm welcome for the Chinese president, erecting a huge portrait of Hu and his wife Liu Yongqing alongside a portrait of King Norodom Sihamoni at the Phnom Penh International Airport.
Tens of thousands people also lined the street, holding the national flags of China and Cambodia, to welcome Hu and the Chinese delegation.