The invention discloses a modular filter element upper cover assembly for a diesel filter. The upper cover assembly comprises an upper shell assembly and a filter element assembly; the upper shell assembly comprises a main body part, a cylindrical rotary cover and a gland part, and a necking part is arranged at the top of the rotary cover; the gland part comprises two or more gland ring sections,and all the gland ring sections are spliced to be a circular ring shape on the same horizontal plane in the circumferential direction; the main body part comprises a cover cylinder, a shoulder part and a connecting cylinder which are sequentially connected from top to bottom; and the filter element assembly comprises a central tube, a filter layer with an annular section, a filter element upper end cover and a filter element lower end cover, and a spiral gas guide groove used for guiding gas is formed in the outer wall of the central tube. According to the upper cover assembly, the gas in fuelcan be prevented from being accumulated at the central tube of a filter element, the sealing performance is high, the structure of the upper cover assembly adopts modular design, the assembly and disassembly of all components are relatively convenient, and the assembly and disassembly operation of the diesel filter is facilitated.