To design the interception guidance with the terminal aspect angle constraint,based on the formula given by other persons,a new solution was brought out,which main idea was to obtain the needed velocity vector by iterating the flight time;then modify the practical velocity during the flight time until the needed and the practical velocities are almost equivalent.

This paper draws out a kind of more optimizing method in guidance control that guides the practical velocity to required velocity by controlling the practical thrust direction in accordance with ideal optimal thrust direction.

When solving required velocity,It real-timely thinks about influence of oblateness of the earth and gives the process of solving required velocity by midcourse trajectory method.

In order to improve the calculation accuracy of required velocity,and efficiently control the hit accuracy of long-range ballistic missile,the paper presented required velocity compensation calculation model that is remarkably affected by the earth eccentricity,gravity anomaly and reentry resistance.

Dummy aim calculation is needed in the close-loop guidance based on the requiring velocity,which only can be acquired by linearization the earth oblateness and reentry aerodynamic force influence.