In order to determine ignition time accuracy of igniter and select timing technology principle of igniter, the particle exterior ballistics theory of extended-range rocket projectile was applied to solve the group centroid differential equations of exterior ballistics of extended-range rocket projectile, the variation regularity of extended-range rocket engine ignition time and angle for range was obtained. The higher precision of extended-range rocket projectile ignition time is, the smaller dispersion of projectiles range is, approximately taking on linear relationship The hybrid base-bleed-rocket extended-range projectile for 155 mm caliber howitzer was used as an example, when the ignition time precision of igniter at ± 1 s or less, the precision of projectile maximum range may meet; while at ± 1 s or more, it is difficult to meet the maximum projectile range precision. An electronic timing technology of igniter should be prior used.