The relationship between charge density and loading pressure,and between laser ignition delay time and charge density of Zr/KClO₄ were studied by fiber inserted laser igniter. The density ranges of 0.94-1.39 g·cm^-3 corresponding to the loading pressure ranges of 5-130 MPa and the delay time ranges of 2.83-0.54 ms corresponding to the density ranges of 1.0-1.38 g·cm^-3 were obtained. With the density below 1.25 g·cm^-3,the ignition delay time changes faster with density,and tends to be stable when the density overpasses 1.30 g·cm^-3,with the shortest delay time in 0.54 ms. When the density is lower,such as below 1.07 g·cm^-3 and the corresponding loading pressure is less than 30 MPa,scattering of experimental data is bigger.