Three new diterpenoids, yuexiandajisu D (1), E (2) and F were isolated from the roots of Euphorbia ebracteolata, along with eight known diterpenoids, jolkinolide B (4), jolkinolide A, ent-11α-hydroxyabieta-8(14),13(15)-dien-16,12α-olide (6), ent-(13S)-hydroxyatis-16-ene-3,14-dione, ent-3β,(13S)-dihydroxyatis-16-en-14-one, ent-3-oxokaurane-16α,17-diol, ent-16α,17-dihydroxyatisan-3-one and ent-atisane-3β,16α,17-triol. The structures of all compounds were deduced using spectroscopic methods and confirmed for 1 and 2 by single-crystal X-ray diffraction. A biogenetic pathway for the formation of 1 and 2 is proposed briefly. Cytotoxic activities were evaluated against ANA-1, B 16 and Jurkat tumor cells. Jolkinolide B (4) displayed modest activity on ANA-1, B 16 and Jurkat tumor cells with IC50 values 4.46 × 10 - 2, 4.48 × 10 - 2, 6.47 × 10 - 2μM, and ent-11α-hydroxyabieta-8(14), 13(15)-dien-16,12α-olide (6) showed significant activity against ANA-1 and Jurkat cells with IC50 values 7.12 × 10 - 3 and 1.79 × 10 - 2 μM. Compound 1 was found to be slightly active against ANA-1 cells with an IC50 value 2.88 × 10 - 1μM. Structure-activity relationships of isolated compounds are also discussed.