Based on flow control valve and pressure following element, an improved interconnected hydro-pneumatic suspension was presented. The suspension system achieved rigid-flexible status switching smoothly through effective combination of flow control valve and pressure following element, lifting synchronization of heavy construction vehicle was finally realized. Hydraulic system simulation model of interconnected hydro-pneumatic suspension was established in AMESim and simulation analyses for synchronization performance were carried out at variable load conditions. The test bench was set up and the experimental research was performed. Experimental results showed that synchronization error was less than 2.5 mm in the lifting process and suspension cylinder did not appear jitter when rigid-flexible status switching. The agreement between the simulation results and the experimental data proved the feasibility of the improved interconnected hydro-pneumatic suspension and the accuracy of the simulation model.