Four different experssion vectors were constructed by cloning foreign gene which encode Schistosoma japonicum 26K antigen(Sj26GST) into Escherichia coli-Mycobacteria shuttle plasmid pBCG-2000 and their expression efficiency were investigated in Mycobacterium smegmatis. The plasmid which contains promoter of human Mycobacterium tuberculosis heat shock protein 70(hsp70) was digested with NcoⅠ and modified with two different ways to lead to two kinds of SD squences, and then ligated with Sj26GST encoding gene. The DNA fragment contained hsp70 promoter and Sj26GST gene was cloned into pBCG-2000, and finally four recombinant mycobacterial expression vectors that are different in SD sequence, orientation and copy number were selected. The expressed native recombinant Sj26GST(rSj26GST) could be observed on SDS-PAGE about at the molecular weight of 26 ku obviously. Analysis with protein density scanning indicated that the expression efficiency that containing double-copy promoter-foreign gene vector was the highest and the expressed protein was about 1.6 folds than that of others. The cloning direction and SD sequence had no significant effect on expression efficiency.