IgE plays a key role in type I hypersensitivity reactions. The blocks of IgE binding to its high affinity receptor FcεRI can efficiently eliminate allergic reaction. The sFcεRIα/mIg(IgG2) was constructed by gene fusion of the extracellular portion of α subunit of FcεRI receptor with human IgG2 hing region, CH2 and CH3 region. The chimera could be a markedly longer plasma half-life than the soluble extracellular domain. This chimeric protein was produced by transfecting Chinese Hamster Ovary cells (CHO). Following affinity purification, the apparent mol. weight of sFcεRIα/mIg(IgG2), which showed high affinity with human and mouse IgE, was above 170 kDa. A good foundation for industrialization of this new engineered soluble protein for type I hypersensitivity diseases was provided.