Abstract: Objectives To study the significance of fibrin related markers such as fibrin monome (FM), D-dimer (D-D), fibrinogen and fibrin degradation products (FDP) in diagnosis of pre-disseminated intravascular coagulation (pre-DIC) state in children with severe pneumonia. Methods A total of 213 children with severe pneumonia in pediatric intensive care unit were divided into pre-DIC group and case control group according to the occurrence of pre-DIC. And 40 healthy children were included as normal control group. FM、D-D、FDP、prothrombin time (PT)、activated partial thromboplastin time (APTT)、fibrinogen (FIB)、platelet count (PLT)、thrombomodulin (TM) levels were analyzed. Receiver operating characteristic curve was used to evaluate the above indexes. Results All the markers but FIB showed significant difference among the three groups (P< 0 . 05 ). The differences of FM、D-D、FDP、APTT in paired comparison among the three groups were also significant (P< 0 . 01 ), Pre-DIC group had the highest level and case control group was the second. Pre-DIC group had higher PT than that of the other two groups (P< 0 . 05 ), but PT levels in normal control group and the control group are of no significant difference (P> 0 . 05 ). Compared with those in normal control group, TM and PLT levels were significantly higher in the other two groups (P< 0 . 01 ), but the differences of TM and PLT in pre-DIC group were not significant in comparison to those in case control group (P> 0 . 05 ). FM、D-D、FDP had larger area under curves (AUC) for pre-DIC than other indexes ( 0 . 84、0.76、0 . 64 , respectively). The AUC for the joint detection of the three indexes was 0 . 85 . Conclusions Fibrin related markers such as FM、D-D and FDP are valuable indexes in diagnosis of pre-DIC state in children with severe pneumonia, the joint detection of the three indexes would help to improve diagnostic accuracy.