Objective：To determine the total polyactetylenes in Wahlenbergia marginata (Thunb.) A.DC.．Method：Using detection wavelength and lobetyolin as the index component，the polyacetylenes substances in Wahlenbergia marginata (Thunb.) A.DC. extract were determined through ethanol reflux extraction and ultraviolet spectrophotometer．Results：Sample size showed a good linear realationship at the range of 4~28μg/mL, precision, stability, repeatability and recovery are achieved．Conclusion：This method is easy, rapid and reiliable．