Here, we suggest a facile method to acquire double gyroid (DG) phase from the self-assembly of chiral block copolymers (BCPs*), polystyrene-b-poly(l-lactide) (PSPLLA). A wide region for the formation of DG can be found in the phase diagram of the BCPs*, suggesting that helical phase (H*) from the self-assembly of BCPs* can serve as a stepping stone for the formation of the DG due to an easy path for orderorder transition from two-dimensional to three-dimensional (network) structure. Moreover, the orderorder transition from metastable H* to stable DG can be expedited by blending the PSPLLA with compatible entity. Unlike the conventional way for blending BCP with homopolymer, PSPLLA blends are prepared by using styrene oligomer (S) to fine-tune the morphologies of the blends at which the molecular weight ratio of the S and compatible PS block (r) is less than 0.1. Owing to the use of the low-molecular-weight oligomer, the increase of BCP chain mobility in the blends significantly reduces the transformation time for the orderorder transition from H* to DG. Consequently, by taking advantage of degradable character of the PLLA, nanoporous gyroid SiO2 can be fabricated using hydrolyzed PSPLLA blends as a template for solgel reaction followed by removal of the PS matrix.