This paper discusses the fundamentals, technology, and effectiveness of various radioactivity methods including the Rn tube method, {alpha} track method, {alpha} card method, surface {gamma} energy spectrum method, emanation method, activated carbon sorption method, {sup 210}Po method and water uranium content method while they are applied to locating natural gas in Machang area. The results show that the radioactive anomalies happen to spread over a nose delineated by seismic survey which has been confirmed to be a gas-bearing structure by drilling. This provides strong evidence on the effectiveness of radioactivity methods applied to natural gas exploration.