Block copolymer micelle has attracted great attention as an effective drug delivery system. It has many merits, such as increasing the solubility of hydrophobic drug, prolonging the in vivo drug circulation time, improving drug stability and enhancing the therapeutic effect of anticancer agents. Micelle morphology plays an important role in its drug loading, in vivo distribution and pharmacokinetic behavior. Here in this paper we provided a review of the critical factors affecting the morphology of block copolymer micelles (polymer, preparation factors, drug and others) for future reference.