The new round of deregulation and reform of powerindustry in China are push forward steadily and achieve remarkable success. The combined operation of spot markets and ancillary services markets will be the key problem of electricity markets construction in the next step. Variable generation resources jointly competing in the electricity markets will be the inevitable development trend of China. Firstly

a combined operation mode of spot and ancillary services markets is processing by considering vari able generation resources. The optimization clearing model of energy and ancillary services markets are also constructed. The thermalunits

hydro units

wind units and solar units are all considered in the model and their operation constraints should be satisfied. Finally

the numerical examples are performed to validate the effectiveness of the proposed model and to analyze the clearing results and benefits of the combined operation mode.