How to reduce immune response is an unprecedented challenge for rAAV gene medicine. Recent studies suggested that lowering dosage of the vector used could reduce immune response caused by rAAV gene medicine. Nevertheless, it would also decrease the transgene expression, leading to failure of gene treatment. It is therefore important to take appropriate steps to maintain high gene expression level and pharmacodynamic, while the dosage of rAAV used is reduced. Here, steps to enhancing gene therapy, such as optimization of the administration, reconstruction of the viral vector and selection of the promoter, are discussed in order to achieve maximum outcome.