Objectives To investigate the role of angiogenic T cells (Tang) and endothelial progenitor cells (EPC) in the pathogenesis of preeclampsia. To explore the relationship between Tang and EPC. Methods From Mar 2013 to Aug 2014, 40 patients diagnosed preeclampsia (PE) and delivered in Hunan Provincial People′s Hospital. A total of 20 of them were defined as the mild preeclampsia group and the other 20 cases were recruited as the severe preeclampsia group. And 24 healthy pregnant women wererecruited as the control group. The percentage of Tang and EPC in peripheral blood mononuclear cells (PBMC) were determinated by flow cytometry between 28 and 40 gestational weeks. Results (1) There was no significant difference in the age, pre-pregnancy body mass index(Pre-BMI) or gestational age among the three groups (P>0.05). The differences of blood pressure among the three groups were statistically significant (P<0.05). The gestational week at delivery, the birthweight of the neonates and the 1 minute Apgar score in the severe preeclampsia group were lower than those in the mild preeclampsia group and the control group, with statistically significant differences (P<0.05). The morbidity of neonatal asphyxia in the severe preeclampsia group was 35%(7/20);and in the mild preeclampsia group it was 5%(1/20), with statistically significant difference( P<0.05). (2) The percentage of Tang in maternal peripheral blood was(52.7 ± 8.0)%, (47.5 ± 8.8)% and (45.5 ± 8.7)% in the control group, the mild preeclampsia group and the severe preeclampsia group, respectively. The difference among the three groups was significant (F=4.248,P<0.05), and SNK q analysis showed there was significant difference between the control group and the severe preeclampsia group(P<0.05).While there was no statistically significant difference between the mild and the severe preeclampsia group, nor between the control group and the mild preeclampsia group(P>0.05). (3) The percentage of EPC in maternal peripheral blood was (0.16±0.07)%, (0.09±0.07)%and (0.08±0.05)%in the control group, the mild and the severe preeclampsia group, respectively. Analysis of variance showed that difference among the three groups was significant (F=9.351, P<0.05). The percentage of EPC in the mild or the severe preeclampsia group was significantly higher than that of the control group(P<0.05). (4) There was no statistically significant correlation between the Tang level and the EPC level in the control group ( r=-0.325, P>0.05). In the preeclampsia group (including mild and severe cases), there was positive correlation between the Tang level and EPC level (r=0.667, P<0.01). The positive correlation between Tang level and EPC level were proved respectively in the mild preeclampsia group (r=0.803, P<0.01) and the severe preeclampsia group (r= 0.520, P<0.05). Conclusions The number of Tang had some correlation with the pathogenesis of preeclampsia. The percentage of Tang had positive correlation with the level of EPC in women with preeclampsia. Tang might have some influence on the change of EPC′ level. Tang together with EPC were likely to contribute to the angiogenesis in preeclampsia.