President Mahinda Rajapaksa received Xi and his wife Peng Liyuan at Colombo airport on their arrival from the Maldives.
Xi, also general secretary of the ruling Communist Party, is the first Chinese leader to visit Sri Lanka since 1986.
Since the advent of Rajapaksa's presidency, Sri Lanka has looked up to China as its main development partner.
At least 20 bilateral agreements in the power sector, industry, sea reclamation and water supply and several other areas of engagement running into multi-billion-dollar investments are to be signed during Xi's two-day visit.
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China has become Sri Lanka's largest development partner with projects varying from airports, sea ports, road infrastructure and power generation.
China has become Sri Lanka's second largest trade partner and second largest source of imports. In 2013, China became Sri Lanka's largest investor and bilateral trade reached USD 3.62 billion.
Xi's visit is also expected to vigorously advance the development of the Silk Road Economic Belt and the 21st century Maritime Silk Road (MSR), as Sri Lanka has shown strong support for the two China-proposed initiatives.
Xi's visit to Colombo, the first of its kind since late President Li Xiannian's state visit in 1986, is "important" to the development of bilateral ties, Rajapaksa has said.
Sri Lanka has emerged as a major ally of China in India's backyard. Xi would leave for India tomorrow from Colombo.