Abstract: The dynamic rules of quantitation and inclusion of glandular scales during flowering of Schizonepetae spica were evaluated by measuring the calyx radius and glandular scale density. Quantitative study of six types of monoterpenoids (β-myrcene, d-limonene, dl-menthone, menthofuran, pulegone, and β-caryophyllene) in glandular scale inclusion was performed using gas chromatography during flowering. Most glandular scales were formed during the pre-flowering stage. The number of glandular scales declined after blossoming due to environmental factors. The metabolism of glandular scale inclusion was obvious and the pulegone accumulated during flowering. The quantity and inclusion of glandular scales were generated before blossoming. However, menthone, menthofuran and β-caryophyllene were still in a state of high metabolism during the later stage and their contents affected the efficacy of Schizonepetae spica. Therefore, the D₁₀ period was determined as the optimal harvest time for Schizonepetae spica.