When the hybrid hydraulic excavator worked in a low load and high battery SOC value state, the maintenance of the engine working would cause unnecessary loss during energy conversion, therefore it was required to shut down the engine at this moment. Then a fuzzy logical control algorithm based on the engine on/off state switch was proposed for the hybrid hydraulic excavator. By comprehensively evaluated the current external load level, value of battery SOC and the duration of engine former state, the engine on-off state switch rules and trigger condition were established, also, parallel or pure electric driver system patterns was formed. By using MATLAB/Simulink to establish a dynamic mathematical model, the power system control performance and fuel consumption were analyzed after the application of the algorithm. The results showed that the fuzzy logic control algorithm had strong applicability for the external load changes, and the engine on/off state switch could reduce the redundancy of the energy conversion process, the machine fuel consumption when the excavator is in a low-load condition with high battery SOC.