The strong haemolytic toxicity of Pulsatilla saponin A (PSA) has hampered its clinical development as an injectable anticancer agent. To circumvent this challenge, twenty PSA derivatives with C ring or C-28 or C-3 modifications were synthesized and evaluated for cytotoxicity against seven selected human tumor lines, as well as for haemolytic toxicity. Structure-activity relationship (SAR) and structure-toxicity relationship (STR) correlations were also elucidated. Compared with PSA, compound 22 showed a better balance between haemolytic toxicity (HD50 > 500 μM) and cytotoxicity toward lung cancer cells A549 (IC50 = 4.68 μM). Molecular studies indicated that 22 was liked to lead to G1 cell cycle arrest and therefore, 22 may be a potent antitumor drug candidate.