Abstract: In order to meet the burst height requirements of a new generation long-range guided rocket projectile, a novel large dynamic optional burst height fuze based on phased array detector was proposed and analyzed in this paper. Due to the burst height of the proposed single-type fuze was assigned to be larger range, optional burst height, satisfying the burst height of larger power warhead and electromagnetism pulse warhead, adapting the discharge height of composite warhead, improving the precise strike ability for army corps and so on, a burst height calculation method was proposed based on millimeter phased array detector for the optional burst height fuze. Firstly, integrating the height measure data of the phased array detector and the inertial navigation data, the height of the rocket was calculated in real time to realize the burst height control. Then the fusion results were regarded as initial value of inertial navigation height measurement to calculate the height at next moment, reducing the measurement error caused by time accumulation and improving the height measurement accuracy. Simulation results show the validity of the method and the calculation precision of the burst height.