Nowadays, spinal anaesthesia plays a very important role in Cesarean. However, side-effects between doses and the appropriate dose of local anaesthesia are still different. Ojectives: This article is to assess the side-effects among doses. Subjects and methods: The study included 365 parturients who were divided into three groups: Group I with 122 parturients, Group II: 122 parturients and Group III: 121 parturients. These patients underwent the spinal anaesthesia in sitting position and the puncture position is L2-3. This research applies the retrospective random test study design, including the comparison among the three groups of I, II and III. Results and discussions: The rate of hypotension during the operation in Group III is higher than that of Group II with p0.05. The patients in Group I demands higher dose of fentanyl and ketamine. The rate of nausea, vomit in operations of Group III (37.2 percent ) is much higher than the rate of 3.3 percent in Group II and Group I (1.8 percent ). This difference has the statistic meaning (p 0.001). The rate of frisson during the operation in Group III (40.5 percent ) is clearly higher than that in Group II (4.1 percent ) and Group I (0.8 percent ). This difference has the statistic meaning (p 0.001). The post-operative adverse effects in three groups are not different with p 0.05. Therefore, for the rate of vomit and frisson, Group I and Group II has the least undesired effects compared with Group III (p 0.05). This difference has the statistic meaning with p 0.05. Conclusions: The dose 8mg bupivacain has lower rate of undesired effects during the operation than the doses of 10mg and 7mg.