Efficient and accurate evaluations of the rare event probability and global reliability sensitivity are crucial yet challenging tasks for the safety design of static and dynamic structures with uncertainties. This study establishes a novel level-wise representative points increment strategy for direct probability integral method (DPIM) [1], which calculates accurately rare event probabilities (less than 10−3). Additionally, the single-loop algorithm based on DPIM for global reliability sensitivity analysis is proposed. Firstly, it is clarified that the error in reliability assessment using DPIM is caused by the imprecise simulation of important subdomains. The idea of increasing the number of important points is advanced to improve the precision of reliability assessment. Subsequently, inspired by subset simulation, the level-wise representative points increment strategy [2] is proposed. This strategy effectively and adaptively adds representative points within important subdomains by selecting new points from the low-level points. Embedding the points increment strategy into DPIM forms a unified and efficient method for rare event estimations of static and dynamic structures. Secondly, the probability density integral equation is established over the failure domain to solve for the conditional probability density function of random variables. In this way, DPIM efficiently calculates global reliability sensitivity with a single reliability estimation. Finally, the accuracy and efficiency of the proposed method are demonstrated in three typical examples by comparing with Monte Carlo simulation (MCS), Quasi-MCS and importance sampling. The results indicate that the proposed strategy significantly improves the accuracy of reliability and global sensitivity assessment employing DPIM, and fulfils a versatile and precise analysis of rare event probabilities and reliability sensitivity in both static and dynamic systems.