The condensates from the Yacheng Gas Field, Ying-Qiong Basins, have unusual chemical characteristics, with distribution dominated by terpanes and steranes derived from higher-plants. Pr/Ph ratios (6-11) are very high. Drimane, cadinanes and homocadinanes exist in high concentration. Anomalously abundant 18α(H)-oleanane and remarkably abundant bicadinanes are present in Yacheng condensates, while 17α(H)-hopanes are in extremely low concentration. Taraxastane and significantly abundant 17α(H)-diahopanes occur in the condensates. In addition, a number of C 29 and C 30 unknown pentacyclic triterpanes were monitored in the condensates, some of which are abundant. The unknown compounds may be terrestrial biomarkers or their occurrence may suggest a sub-oxic (dyacrobic) clay-rich depositional environment. C 29 homologues are relatively predominant in regular and rearranged steranes. The concentration of diasteranes is markedly higher than that of regular steranes. The characteristics of Yacheng condensates are indicative of terrestrial source input. Based on condensate-condensate and condensate-rock correlations, combined with results of studies on sedimentary facies. Yacheng condensates may be sourced from Yacheng and Lingshui Formations in the Qiongdongnan Basin. The maturity of Yacheng condensate is relatively high, at late oil window stage (corresponding to 0.9%-1.3% R 0), based on sterane and terpane maturity parameters. The condensates from the Yacheng Gas Field, Ying-Qiong Basins, have unusual chemical characteristics, with distribution dominated by terpanes and steranes derived from higher-plants. Pr / Ph ratios (6-11) are very high. Drimane, cadinanes and homocadinanes exist In high concentrations. Anomalously abundant 18α (H) -oleanane and remarkably abundant bicadinanes are present in Yacheng condensates, while 17α (H) -hopanes are in extremely low concentration. Taraxastane and significantly abundant 17α (H) -iahopanes occur in the condensates. In addition, a number of C 29 and C 30 unknown pentacyclic triterpanes were monitored in the condensates, some of which are abundant. The unknown compounds may be terrestrial biomarkers or their occurrence may suggest a sub-oxic (dyacrobic) clay-rich depositional environment . C 29 homologues are relatively predominant in regular and rearranged steranes. The concentration of diasteranes is markedly higher than that of regular steranes. The char acteristics of Yacheng condensates are indicative of terrestrial source input. Based on condensate-condensate and condensate-rock correlations, combined with results of studies on sedimentary facies. Yacheng condensates may be sourced from Yacheng and Lingshui Formations in the Qiongdongnan Basin. The maturity of Yacheng condensate is relatively high, at late oil window stage (corresponding to 0.9% -1.3% R 0), based on sterane and terpane maturity parameters.