Objective To investigate the expression and the role of Tim-3 and Th-17 in ITP patients and to research their clinical application. Methods Total 42 active ITP patients and 39 healthy donors were recruited in this research. The expressions of Th17 and CD4+ CD25+ Treg were measured with flow cytometer. IL-17, IFN-γ levels as well as IL-4 plasma levels were determined by ELISA. The mRNA expression of Tim-3, IFN-γ, IL-4 and T-bet were measured using RT-PCR in all samples. Results The expression of Th17 cells in ITP patients was (2.41 ± 1.43 )%, which was significantly higher than control group ( 1.08 ± 0.59)% ( t = 5.35, P < 0.05 ). But the percentage of Treg in ITP patients was ( 1.64 ±0.74)%, which was lower than control group (3.12 ±0.52)% (t = 10.33, P <0.05). The levels of IL-17 in plasma of ITP and controls were ( 14.42 ±6.37) ng/L and ( 13.91 ±4.47) ng/L respectively (t =0.42, P > 0.05). The level of IFN-γin plasma of ITP was (55.74 ± 15.25 ) ng/L, which was higher than control group (31.33 ± 12.99) ng/L (t = 7.72, P < 0.05 ). The level of IL-4 in the plasma of ITP was (7.42 ± 1.50) ng/L, which was lower than controls ( 18.17 ± 5.19) ng/L ( t = 12.87, P ＜ 0.05 ). Both IFN-γand T-bet mRNA levels were up-regulated in active ITP patients by the factor ( 8.57 ± 3.44 ) -fold and (3.34 ± 1.32)-fold than control group (t = 13.21,6.41 ,P <0.05). The decreases observed in IL-4 and Tim-3 were (0.25 ±0.15 )-fold and (0.29 ±0.15)-fold respectively in ITP patients compared with control group (t=10.02,9.61,P＜0.05 ). Conclusion The imbalance of Th17/Treg and the decrease of Tim-3 might be important determinants in the evolution of ITP.