Abstract: Objective To explore the clinical significance of detecting platelet parameters in the diagnosis and efficacy-evaluation of adult severe primary immune thrombocytopenia (ITP). Methods Thirty-four adult patients with primary ITP admitted in our hospital served as observa-tion group while another 30 healthy people undergoing physical examination as control group. Platelet parameters on both groups before treatment and in observation group 3and 7 days after treatment were observed.Results Before treatment,observation group was evidently lower in platelet count (PLT)and plateletocrit (PCT)and obviously higher in mean platelet volume (MPV) than control group (P <0.05),but there was no significant difference in platelet distributive width (PDW)(P >0.05).Compared with treatment before,PLT,PCT,MPV increased more markedly 3 d after treatment while PLT,PCT,PDW increased significantly 7 days after treatment in obser-vation group (P <0.05).Conclusion Platelet parameters have important clinical significance in e-valuating the progression and efficacy of adult patients with severe primary ITP.