A theoretical approach combining self-consistent-field theory (SCFT) for fluids and density functional theory (DFT) for particles was applied to investigate the self-assembly behavior of amphiphilic diblock copolymer/nanoparticle mixture in dilute solution. Two kinds of hydrophobic nanoparticles are studied: one is that the particles are selective to hydrophobic blocks but are incompatible with hydrophilic blocks, and the other is that the particles are nonselective to hydrophobic and hydrophilic blocks. For both cases, the self-association of amphiphilic block copolymer/nanoparticle mixture is observed, and the nanoparticles are spatially organized in the clusters. The aggregate morphologies can be tuned by the particle radius and particle volume fraction. For the selective particles, the aggregate morphologies of amphiphilic block copolymer/nanoparticle mixture can experience a transition from vesicles to mixture of circlelike and rod micelles as the particle radius and/or particle volume fraction increase. For the nonselective nanoparticles, the large compound micelles are produced instead of the vesicles. The large compound micelles transform to the mixture of large compound micelles and circlelike micelles with an increase in particle volume fraction and/or radius. The distribution of nanoparticles in the clusters is also affected by the particle radius and volume fraction. For both cases, when the values of nanoparticle radius and/or volume fraction are small, the nanoparticles are almost uniformly distributed in the cores of micelles. However, the particles tend to localize near the interfaces between the core and shell with increasing particle volume fraction and/or radius.