To improve penetration ability of jet at large burst height, combined with improvement of some armor penetration war-head, the rapture and velocity distribution of the jet at large burst height were studied through experiments. The result indicates that the rapture and velocity distribution of the jet at large burst height are not continuous, the velocity of jet head is not linear, with the cap of velocity between frontal particle and latter is 1478.1m/s;The velocity of jet latter is linear; with the cap of velocity between particles are 124m/s. The armor penetration ability of the jet is controlled by its height velocity head and the jet velocity when arriving target is not less than 5000m/s.