Abstract: To reaserarch the dynamic change of volatile components in Herba Hyperici Japonici, and provide scientific basis for determining the best collecting time， the volatile components of Herba Hyperici Japonici from different harvesting time were analyzed by HSGC/MS. The relative content of the components were determined with peak area normalization method, and the dynamic change of 6 main boiactive components were determined. The results show that 48 constituents are separated and identified. There are 22 co-containing compounds in Herba Hyperici Japonici from different harvesting time. The accumulation of volatile components show a regular pattern. The main volatile components in Herba Hyperici Japonici are the highest in the traditional harvesting time.