This paper studies the influence of reserves, production and other factors on the market capitalization (market cap) of publicly traded US oil and gascompanies.The paper provides two innovations to the literature. First, based on the relationships among influencing factors, three empirical analytical models are established and the significance and impact intensity of the influencing factors are tested and studied.Second, the effects of various influencing factors on company market cap are studied in three scenarios of oil price fluctuation, high oil price and low oil price.The results show that the impact of oil and gas reserves and production on the market cap of US oil and gas companies is gradually increasing.The return-on-assets ratio and solvency have impact on the company market cap only in high price scenario.The financial leverage ratio of US listed oil and gas companies is on the rising, but investors have not undervaluedthe oil and gas companies because of it.The impact of reserve to production ratio on the market cap of oil and gas companies is uncertain.In the period of high oil prices, the market cap of oil and gas companies can be explained by reserves, production, reserves to production ratio, return-on-assets and solvency.However, when oil prices are low, other factors other than reserves and production are not significant. Besides, the market cap of oil and gas companies is affected by random factors.