The objective of this study was to explore the molecular defects in two Chinese families with hypodysfibrinogenemia. The coagulation method and immunoturbidimetric method were used to detect plasma fibrinogen activity and plasma fibrinogen antigen. The fibrinogen genes were amplified by PCR, and suspected mutations were confirmed by reverse sequencing. Bioinformatics and model analysis were used to study the conservatism and harm of the mutations. Study showed that the Fg:C and Fg:Ag of the probands of the two families were reduced, respectively, to 0.80g/L, 0.92g/L and 1.35g/L, 1.42g/L; gene analysis revealed that the proband 1 had a heterozygous missense mutation of c.688T>G (p.γPhe230Val) in exon 7 of the FGG gene; the c.2516A>C (p.AαAsn839Thr) heterozygous missense mutation in exon 6 of the FGA gene was got by the proband 2. These mutations found in this study might be related to the hypodysfibrinogenemia.