With the deregulation of demand-side market, the marketization of demand response（DR）instead of the conventional power demand - side management is becoming a trend under the background of power market reform. A series of provinces and cities including Guangdong have implemented the market trade programs of DR. The Guangdong DR program’s elements are introduced including start-up condition, trading process, measurement approach and financial source, etc. Then, the market clearing mode and price mechanism for the bidding on the same platform of DR market actors and generators are proposed, and the role of two clearing modes in DR’s participation in spot market is analyzed. Finally, the advantages and disadvantages of different clearing mechanisms and their impact on market actors are verified by market simulations.