This article analyzed technology needs assessment reports of 20 developing countries by literature analysis,questionnaire and expert consultation. Energy and agriculture are prior fields of mitigation for developing countries,and waste treatment and industrial energy efficiency are second priority fields. Energy industry, transport and household energy conservation are sub-fields of energy sector. Crop management improvement,agriculture waste management and livestock dietary improvement are prior technologies of agriculture sector. Agriculture and water resource are prior fields of adaptation for developing countries, and coastal zone management and health are second priority fields. Crop management, land management, farmland irrigation,pasture management and livestock management are prior technologies of agriculture sector. Rainwater harvesting,water leakage control,urban sewage treatment and reuse,climate monitoring and early warning systems,wells technologies are prior technologies of water sector. Tackling climate change by science and technology has become the consensus of most of developing countries. Different countries have different technology needs,but cost effective technologies and capacity building are most developing countries' preferences. The barrier analysis shows that finance and market,capacity,information, regulation and policy, intellectual property and technology, tradition culture and awareness are the main barrier for technology transfer and diffusion for technology receiver. Finance,coordination of government, information, willingness and motivation are the main barrier for technology supplier,taking china as an example. Suggestions for China to strengthen south-south cooperation to address climate change through science and technology are also given. First, develop action plans to promote scientific and technical cooperation on climate change,and strengthen the coordination of different ministries in charge of foreign aid. Second,strengthen bilateral and multilateral cooperation to enhance China's international discourse in climate change through multi-level cooperation mechanism. Third, guide and encourage all-round, multi-channel technology transfer to developing countries. Forth,strengthen capacity building of developing countries to address climate change through science and technology. Fifth, broaden the sources of funds through various channels,and optimize the structure of capital expenditure. Finally, complete set of policies and measures to promote China's enterprises to participant south south scientific and technical cooperation.