A series of spatiotemporally resolved surface photovoltage techniques were used to investigate the pho-togenerated charge transfer process within sub-picosecond to second timescale and at sub-micrometer level on single-particle cuprous oxide photocatalyst. A spatiotemporal charge transfer image was pictured. It is found that the high efficiency in charge separation of the facet-specific cuprous oxide single-particle originates mainly from the ultrafast quasi-ballistic inter-facet hot electron transfer process. These findings give a fascinating and deep insight into the photoinduced charge transfer mechanism in semiconductor photocatalyst, and pave a refreshed way to developing photocatalyst.