Abstract: To raise the calculation precision of active structural control, the closed-loop and closed-open- loop control algorithms for instantaneous structural optimizationwere improved based on the active structural control strategy and the precise integration method (PIM). Different from the traditional solutions of structural control equations, it is not required for this improved algorithm to solve the characteristic vector and the eigenvalues of a dynamic state matrix. As a result, the precision of instantaneous structural control can be raised. As an example, this algorithm was used for the control simulation of two structures. The results showthat the algorithm is convergent and not sensitive to time-step, and its calculation precision can be controlled easily.