Abstract: This paper reports the circular dichroism and octant rule projection of 5 diterpenoids from Mallotns anomalus (compounds 1～5) and 3 sesquiterpenoids tussilagones (compounds 6～8): they are new compounds. Using ketone octant rule, planar cyclohexenone rule, β, γ-unsaturated ketone rule and Harada rule, the nature of A/B and B/C ring fusion was determined, thus their, absolute configurations were assigned.