The feasibility of improving ignition and combustion performance of methane by ozone addition has been studied in the present work. First, combustion of a lean methane/air mixture with ozone addition was conducted by using a constant volume combustion bomb. Results showed that ozone could extend the lean combustion limit and accelerate flame speed. Then, chemical reaction kinetic analysis was adopted to obtain ignition delay time and laminar flame speed which were used to analyze the influence of ozone on ignition and the combustion performance of the lean methane/air mixture, respectively. Analysis carried out with different equivalence ratio, initial temperature, and pressure showed that ignition delay time was shortened obviously with ozone addition. The peak concentration of CH2O increased and the time of peak concentration appearance advanced with ozone addition, which indicated that the beginning time of the low temperature reaction was advanced with ozone addition and thus improved ignition performance. Laminar flame speed could be accelerated obviously with ozone addition in different equivalence ratio, especially under the condition of research. Concentration of OH and other intermediate products with ozone addition was compared and results showed that ozone could increase the amount of OH and other products, thus improve combustion performance. The results obtained in this study showed that ozone could shorten ignition delay time and accelerate burning velocity of the lean methane/air mixture.