The invention discloses a general bacillus subtillis combination expression vector for improving the expression level of alpha-amylase. The invention relates to the general bacillus subtillis combination expression vector including the following parts: a bacillus subtillis promoter sequence, a multiple cloning site sequence for combining components possibly related to expression regulation, and an escherichia coli copying initiation sequence. The vector can be stably copied in escherichia coli and can be combined with bacillus subtillis chromosomes for stable expressing. After the vector is combined with bacillus subtillis chromosomes, the expression level of alpha-amylase in bacillus subtillis is obviously improved.