: To identify potential mutations of F11 gene in a family with hereditary coagulation factor XI (FXI) deficiency and explore the molecular pathogenesis. The FXI activity and FXI antigen were tested with clotting assay and ELISA, respectively. The FXI gene was amplified by PCR with direct sequencing. Three bioinformatics softwares were used to study the conservatism and harm of the mutation. The proband had a prolonged activated partial thromboplastin time (84.2 s), whose FXI activity and FXI antigen were 3.0 and 8.6%. Gene sequencing revealed that the propositus carried a heterozygous nonsense mutation c.738G>A in exon 7 resulting in a p.Trp228stop and deletions mutation c.1325delT in exon 12 resulting in a p.Leu424Cys. Two bioinformatics softwares all were indicated the mutation had affected the function of the protein. The c.738G>A heterozygous nonsense variation and the c.1325delT heterozygous deletion variation are associated with decreased FXI levels in this family, which is the first reported in the world.