China will invest 120 billion yuan ($A20.33 billion) this year to expand the mainland's 3G telecoms network, despite a lower-than-expected number of domestic subscribers as of the end of June, the official Shanghai Securities News said.

By 2011 China will have invested a total of 400 billion yuan and hopes to have a 3G network covering most of the country, according to an earlier plan by the country's Ministry of Industry and Information Technology.

Chinese 3G subscribers totalled 25.5 million as of the end of June, while the target number of users by next year is 150 million.

China's three telecom operators, China Mobile, China Telecom and China Unicom, spent about $US21 billion building their 3G networks in 2009, following the much-delayed issues of licenses earlier that year.