Nowadays, the power shortage becomes more serious. The new methods of producing electricity power have been paid more and more attentions to. All over the world, the low temperature heat source is very abundant, such as the geothermal energy, solar energy and industrial waste heat. In this paper, a combined power and heating thermodynamic system powered by low temperature heat source based on ORC (organic Rankine cycle) was proposed. The system consists of a heat source system, a screw expander, a hot water generator, a condenser and a feed pump. And the fluid R245fa was selected as the working fluid. From the low temperature heat source, firstly the electricity power and secondly the heating power ware gained. The cycle performance of the system was studied at the typical working condition. And some key factors to the system are analyzed. Also the experiment system was set up, and the experimental performance of the system was studied under the typical working condition. In the period of the experiment, the low temperature heat source is the heat collected from solar. The performance comparison based on the simulation results and the experimental results was done. Also the actual effects of some factors were analyzed to improve the system.