Solar cells based on metal-halide perovskite/TiO heterojunction have demonstrated exceptional high power conversion efficiencies. However, the electron extractor TiO is typically a polycrystalline film processed with solution methods. The crystal face dependent electron extraction from perovskite to this TiO film is still unclear, which is essential for the device performance further optimization. Herein, the ultrafast charge carrier dynamics in CHNHPbI/TiO heterojunctions with rutile TiO single crystals terminated at (100), (001) and (110) faces were systematically investigated. Our results clearly show that the charge carrier extraction from perovskite to TiO is strongly dependent on the TiO crystal face. The (100) face shows the best charge carrier extraction performance with an electron extraction efficiency over 98%. In contrast, the (001) face demonstrates an electron extraction efficiency less than 40%. The hot electron extraction from photo-excited perovskite to TiO has also been clearly revealed with transient absorption. The first-principle density function theory calculations indicate that the electron transfer from CHNHPbI to rutile TiO is more energetically favoured for the (100) and (110) faces than for the (001) face. These findings reveal the hidden role of the TiO crystal facets in electron extraction and its impact on the perovskite solar cell efficiency.