Pattern generation of well-controlled block copolymers (BCPs) with high Flory-Huggins interaction parameter (χ) is important for applications in sub-20 nm nanolithography. We used mixed solvents of dimethylformamide (DMF) and toluene to control the morphology as well as the time to achieve the targeted morphology via self-assembly of BCPs. By precisely controlling the volume ratio of DMF and toluene, well-ordered line, honeycomb, circular hole, and lamellar nanostructures were obtained from a cylinder-forming poly(styrene-b-2vinylpyridine) (PS-b-P2VP) BCP with high-χ. Furthermore, a well-aligned 12nm line pattern was successfully achieved in the guiding template within one minute by using the mixed solvents. This practical method may also be applicable to self-assembly of other BCPs, providing more opportunities for the next-generation sub-10 nm lithography applications.