The oblate propellant with micropores（MPOP） was prepared by chemical foamed process,and the effects of the materials and inner-structure on its electrostatic spark sensitivity were studied by adjusting the distance of discharging and the way of loading. Results show that the lower the bulk density of these oblate propellants is,the higher electrostatic spark sensitivity is. And the smaller the grain diameter of the oblate propellants is,the higher its electrostatic spark sensitivity is. The electrostatic spark sensitivity of MPOP with the bulk density not more than 0.3 g·cm^-3 is apparently higher than nitrocellulose. It is feasible to test the electrostatic spark sensitivity of low-density materials with micropores using this improved method.