Objective: to investigate the effect and side effects of recombinant human interleukin - 11 (rhIL - 11, in Chinese Juheli, produced by Qi Lu Biotechnology CO., LTD) in the second prevention of chemotherapy induced thrombocytopenia (CIT). Methods: Cancer patients with CIT were recruited and were treated with rhIL - 11 (treatment phase, TP), and in the following cycle, all these patients administered with rhIL - 11 24 hours immediately after chemotherapy (preventive treatment phase, PTP). Duration and severity of thrombocytopenia between two phases were compared. Results: for patients in TP or PTP, nadir values of platelet were ($29.28{\pm}20.08){\times}10^9/L$ and ($45.24{\pm}19.66){\times}10^9/L$, duration of thrombocytopenia in TP and PTP was ($11.52{\pm}4.33$) and ($8.20{\pm}+2.77$)days, recovery time was ($19.40{\pm}3.89$)and ($13.44{\pm}3.02$)days, duration of rhIL - 11 administration was ($10.68{\pm}2.46$)and ($6.28{\pm}1.77$)days, number of patients needing platelet infusion was 16and4 respectively, all differences were statistically significant (p value were 0.007, 0.002, 0.000, 0.000, 0.034 respectively). For TP and PTP, number of patients with hemorrhage was 8 and 4, duration of bleeding was ($5.00{\pm}0.82$) and ($4.50{\pm}0.71$) days respectively, with no statistically significant difference. Adverse reactions mainly included fever, edema, arrhythmia, joint pain, fatigue, skin rash, headache, dizziness, etc., all were not statistically significant between TP and PTP. Conclusion: rhIL - 11 could be well tolerated and is effective that could reduce the duration, severity of CIT, platelet transfusion, and incidence of bleeding, as well as shorten the recovery time, duration of rhIL - 11 administration. Thus, rhIL - 11 could be commended in the second prevention of CIT for patients with cancer.