Targeting is critical for successful tumor gene therapy.The adeno-associated virus(AAV) has aroused wide concern due to its excellent advantages over other viral vectors in gene therapy.AAV has a broad infection spectrum,which also results in poor specificity towards tissues or cells and low transduction efficiency.Therefore,it is imperative to improve target and transduction efficiency in AAV-mediated gene therapy.Up to now,researchers have developed many strategies to modify AAV capsids for improving targeting or retargeting only desired cells.These strategies include not only traditional chemical modification,phage display technology,modification of AAV capsid genome,chimeric vectors and so on,but also many novel strategies involved in marker rescue strategy,direct evolution of capsid proteins,direct display random peptides on AAV capsid,AAVP(AAV-Phage),and etc.This review will summarize the advances of researches on the capsid modification of AAV to target malignant cells.