A fusion protein is disclosed. The fusion protein of the invention comprises an Fc fragment of an immunoglobulin G and a bioactive molecule, wherein the Fc is a single chain Fc. The amino acids in the hinge of the Fc is mutated, substituted, or deleted so that the hinge of Fc cannot form disulfide bonds. Methods for producing and using the fusion protein of the invention are also provided.本發明提供一種融合蛋白。本發明融合蛋白包含免疫球蛋白G之Fc片段和生物活性分子,其中此Fc為單鏈Fc。藉由突變、取代或刪除此Fc之鉸鏈的胺基酸,使此Fc之鉸鏈無法形成雙硫鍵。另外本發明更提供製備和使用本發明融合蛋白的方法。