The gene sequence coding the N-terminal domain of LppQ was amplified from Mycoplasma mycoides subsp. mycoides SC (MmmSC) HVRI X strain by PCR using special primers and was cloned into the EcoR I /Sal I sites of pET32a vector to construct the expression recombinant plasmids. The recombinant plasmids were indentified by restriction digestion, PCR and sequence analysis. The gene was overexpressed in Escherichia coli BL21 (DE3) host cell and the soluble protein was purified with Ni-NTA His. Bind purification kits. The amount of recombinant protein reached 53.7% of the total mass of bacterial protein. The purity of recombinant protein reached to over 95 %. The antigen activity of the purified protein was examined with Western blot analysis. The purified protein reacted strongly with the standard positive serum and didn't react with the negative sera of contagious bovine pleuropneumonia(CBPP).