Abstract: In December 2013,the Mexican government approved energy reform act.It marks the end of 75 years national monopoly in energy sector.The reform is aimed to reverse the decline in oil production and assure energy security and economic development.The reform involves amending constitutional,introducing new contract,and reducing governmental intervention.Both opportunities and challenges are facing China's oil companies.The two states have built sound relationship and trust which endows COCs with unique strength on the one hand,COCs faces tremendous competition from IOCs on the other.A good strategy for COCs is starting from refining and engineering sector while reinforce cooperation with independent oil companies and service companies.