A built-up LED street lamp (100) comprises a lamp body and a LED array (107). The lamp body comprises a head section (101), a middle section (102) and a tail section (103). The seal washers (104) are provided in the gap between the head section (101) and the middle section (102), as well as the gap between the tail section (103) and the middle section (102). The head section (101) and the tail section (103) are connected to the middle section (102) by fasteners, respectively. The middle section (102) is a section bar having same cross section at various positions along the longitudinal direction of the section bar. The build-up street lamp with various shape standards can be made with a common mould.