The intervention group will receive rhTPO at a dose of 15000u/d, subcutaneous injection, for 7 consecutive days. It will be terminated when platelet counts(PCs) are increased by 50×10^9/L for 3 consecutive days compared with PCs at baseline, or PCs are more than 100×10^9/L, or the duration of rhTPO is more than 7 days. Time from randomization to administration of rhTPO will be within 24 hours. The control group will not use any platelet-increased drugs.