The invention discloses a method for compiling a program organizing unit, including the following steps: step 1, accessing and compiling program organizing units and subunits according to a depth-first traversal sequence; step 2, merging data areas of the program organizing units and the subunits; step 3, in an instruction area of a parent unit, searching an instruction of calling the subunits, deleting the instruction, inserting an instruction set of the subunits, and carrying out repositioning processing; and step 4, repeating the above operations until the compiling compilation of the topmost program organizing unit. The method can compile the program organizing units and subunits, and supports hierarchical management of structured text programs.