Abstract: To solve the problem of the state parameters constraints at the handover moment between the midcourse and terminal guidance in the hypersonic target interceptions, the interception capability of the true proportional navigation guidance law is analyzed. Firstly, the sufficient and necessary condition for a successful interception and the constraints for the target velocity heading angles are derived by analyzing the relative motion of the interceptor and the target in the terminal guidance phase. Secondly, in the cases where the interceptor fail to satisfy the interception condition against unmaneuvering hypersonic targets, the definition and constitution of the static capture region (SCR) of the true proportional navigation guidance law are given by analyzing the evolving relationships between the interceptor velocity heading angles and target velocity heading angles. Thirdly, aiming at the maneuvering hypersonic targets interceptions, the definition and constitution of the dynamic capture region (DCR) of the true proportional navigation guidance law are derived based on the target velocity heading angles constraints. Finally, three digital simulations are carried out, which validate the rationality and effectiveness of the true proportional navigation interception capability analysis.