There is possibility of circulation loss and collapse in the upper stratum of Jiulongshan region, strong abrasivity and extremely poor drillability in the middle stratum, and multiple field and pressure system in the lower stratum. In order to cope with the abnormal situation, this well is designed to use gas drilling. The stratum is gassing when air drilling was dilled to 1170.28m. Then switch to nitrogen drilling, but when drilled to 1868m, it is wellface collapsed and drill stem blocked and sticking. At last it must finish the gas drilling. The paper records a main gas concentration changes and the handing measures of the abnormal condition during the drilling process, and provides some experiences to gas drilling crews dealing with abnormal condition. In conclusion, gas drilling have more advantage than conventional drilling in preventing circulation loss, stratum gassing without H2S, and abnormal pressure.