Based on the study of Karp’s ski rental model for the classical online leasing problem，this paper considers the multiple online leasing model for continuous relaxation problem with market interest rate．Firstly， we investigate the optimal offline strategy and show the relationship between the optimal offline cost and market interest rate．Then，based on the online characteristics that offline adversary might stop using assets at anytime so that online players may encounter a high-risk situation like no longer using assets shortly after purchasing，we propose a balancing risk strategy and obtain its optimal competitive ratio by using online algorithm and com_x005fpetitive analysis．Meanwhile，we prove that the competitive ratio of the balancing risk strategy is the optimal ratio for this problem．At last，the monotonicity of relevant variables in the optimal competitive ratio is discussed，and the result shows that the competitive performance of online strategy improves significantly with the factor of market interest rate and multi-unit asset，thereby enhancing the online rental decision-making efficiency．