Abstract: The spacecraft operation systems are almost the variable mass mechanics systems.So researching the motion equations of the variable mass system is the basic of studying the space system mechanics properties.Differing form the Tzénoff equations researched by the freezing derivative and the freezing partial derivative,in this paper,the generalized Tzénoff functions of the variable mass mechanics system is constructed by the ordinary derivative and the generalized Tzénoff equations of the variable mass holonomic system and higher-order non-honolomic system expressed by ordinary partial derivatives are generated.All the given motion equations are with new construction form,and the construction of the differential equations has some theory value to the kinetic research of the variable mass system.