In order to improve the consistency of the arc thickness of the oblate spherical propellant and thus the ballistic consistency of the propellant charge, hydraulic grading technology is used to study the hydraulic grading technology of the semi-finished oblate spherical propellant. On the basis of the existing propellant water sieve technology, the analysis of water separation technology is carried out to form a water sieve plus a hydraulic separator for semi-finished propellant screening technology. The results show that compared with the original process, the standard deviation of particle diameter can be reduced by 35%, and the distribution range can be reduced by 31%. The standard deviation of arc thickness can be reduced by 47%, and the range of distribution can be reduced by 24%. Consistency has been greatly improved.