NOVELTY - A junction box assembly comprises junction box (1) and base plate (2), where junction box is assembled with base plate. The junction box comprises insulated housing (10) and pair of conductive terminals disposed in insulated housing. The junction box and base plate both include longitudinal axis (L). A bottom (14) of junction box disposes at least two first openings (11) along the longitudinal axis. The junction box further comprises at least two water-resistant units; and base plate is of a barshape and disposes at least two third openings along longitudinal axis.    USE - Photovoltaic battery module.    ADVANTAGE - The contact area between the junction box assembly and desired mounted regions, is remarkably enhanced, thus ensuring junction box assembly being firmly mounted on desired regions and being unlikely to loosen. It can be securely assembled with base plate, which is unlikely to loosen or be taken apart due to external impact or unintentional force. The junction also has improved water-proof performance and has improved service life.    DETAILED DESCRIPTION - Junction box assembly comprises junction box (1) and base plate (2), where junction box is assembled with base plate. The junction box comprises insulated housing (10) and pair of conductive terminals disposed in insulated housing. The junction box and base plate both include longitudinal axis (L). A bottom (14) of junction box disposes at least two first openings (11) along the longitudinal axis. The junction box further comprises at least two water-resistant units, each of water-resistant units, which is disposed at each of first openings; and base plate is of a barshape and disposes at least two third openings along longitudinal axis. The third openings, first openings of junction box and each of second openings of each of water-resistant units are assembled with one another. An area of each of third openings is smaller than an area of each of first openings. Pairs of wing portions are aligned along both lateral sides of longitudinal axis of base plate, each of pair of wing portions is provided with first preset distance there between. The first preset distance is shorter than width of junction box. An average width of base plate is not greater than 50 millimeter. The water-resistant units have a second opening, where an area of each of second openings is smaller than an area of each of the first openings.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic diagram illustrating a junction box assembly.    Junction box (1)    Base plate (2)    Insulated housing (10)    First openings (11)    Junction box bottom (14)