We report on a passively Q-switched photonic crystal fiber (PCF) laser with Cr4+:YAG as a saturable absorber. Under a pump power of 14.2 W, the maximum pulse energy is up to 630 μJ with a pulse width of 36 ns at a repetition rate of 5.6 kHz. With an intracavity optical parametric oscillator, the passively Q-switched PCF laser is used to generate the signal wave at 1515 nm. The output pulse energy of the signal wave is found to be 140 μJ with a pulse width as short as 1.0 ns at a repetition rate of 3.3 kHz. The very short pulse width leads to the peak power up to 140 kW.