The effects of injection pressure on liquid and vapor phase spray characteristics at different injection timings under ultrahigh injection pressure (>= 160 MPa) were studied by using a planar laser-induced exciplex fluorescence technology in an optically accessible single-cylinder direct injection diesel engine. The injection pressure was changed from 160 MPa to 220 MPa, and the injection timing covered 42 degrees CA to -6 degrees CA of crank angle before top dead center. Results reveal that the ultrahigh injection pressure, which is higher than 160 MPa, can significantly promote spray atomization and evaporation and results in an increase of vapor phase percentage. The inhomogeneity (estimated by the standard deviation of the normalized fluorescence intensity) is improved as injection pressure is increased from 160 MPa to 220 MPa, but the improvement varies clearly with injection timing. It is also revealed that both liquid and vapor phase sprays can be fully developed when L/d(0) >= 90, where L is penetration and do is orifice diameter, at the experimental injection pressure, which is much less than that observed in previous work at lower injection pressures.