Realizing the efficient utilization of photogenerated carriers is a pivotal process to access the efficient transformation of light energy. Herein, we firstly practice a facile template method to synthesize O-doped crystalline/none-crystalline g-C3N4 embedded nano-homojunction photocatalysts (CMCCN-x). This nano-homojunction makes the crystalline phase sufficiently contact with amorphous phase and further facilitates the photoinduced electron transformation. Therefore, the best performance catalyst CMCCN-5 well integrates the advantages of crystal g-C3N4 and amorphous g-C3N4, which exhibits an excellent photogenerated carrier separation ability and abundant photocatalytic hydrogen evolution reaction activity sites. Excellent performance in the separation and use of photogenic carriers endows CMCCN-5 with efficient utilization of photogenerated carriers. Although there is a limited light absorption range (<460 nm), the photocatalytic hydrogen evolution rate of CMCCN-5 is up to 203.66 μmol h−1 under the visible light irradiation, about 86 times higher than pristine g-C3N4. The AQY numbers of CMCCN-5 at 420 nm and 450 nm are up to 26.9% and 14.0%, respectively. Thus, the significant effectiveness is forcefully proved for the facile construction of O-doped g-C3N4 crystalline/none-crystalline nano-homojunction.