Uricase is an important enzyme in purine degradation and receives considerable interests in therapy of hyperuricaemia. But as a heterogeneous protein, it may trigger immunoreactions when applied in human body. To reduce its immunogenicity, we designed three modified uricases, in which bovine lactoferricin was used as molecular modifier and embedded into baboon uricase by recombinant technology. In vitro immunological assay revealed decrease in uricase’s immunogenicity corresponding to the number of modifiers in molecule and the maximum decrease was 48.67%. This study presents the possibility of using small peptide as modifier to reduce the immunogenicity of protein and provides a new clue for molecular modification.