The dynamic models of the hydraulic control,boom and coupling system in descending working conditions of the boom bystem of truck crane were proposed by bond graph method.The dynamic response of the systems was simulated with Matlab.The time domain indices were studied by simulation.At the same time,the dynamic parameters influencing the characteristics of the derricking system of truck cranes were analyzed qualitatively.The methods can be put into practice in truck cranes.At the same time,the methods can m...