Multi-resonant switched capacitor converter canmake efficient use of active and passive components, and hastwo characteristics of high efficiency and highly power density.Therefore, we propose a 9:1 cascaded multi-resonant switchedcapacitor converter and further explore ways to improve theperformance of the converter in this paper. On the one hand, byanalyzing the coupling relationship between the first and secondcircuit topology, we propose a method to reduce the intermediatedecoupling capacitance. On the other hand, by adjusting the deadtime of the control signal, the zero-voltage switch (ZVS) of mostswitching devices is realized, and the efficiency of the converteris improved. Therefore, a 48V-5V resonant converter prototypewith rated power of 120 W, power density of 330 W/in³, peakefficiency of 98.1% and maximum output current of 23.7 A is designed in this paper. From 20% to full load, the efficiency is al-ways maintained at more than 92% (including driving loss), andmost of the loss is reflected in the conduction path, reflecting greatoptimal space and application potential.