The invention discloses a method and a system for developing a shellcode of a *86 platform or a *64 platform fast. The method comprises the following steps: writing a function according to C language, and dynamically acquiring an application programming interface (API); writing the shellcode according to the acquired API; compiling the written shellcode with a compiler, so as to generate an EXE file of the *86 platform or the *64 platform; and extracting the shellcode from a code section of the EXE file with an extracting tool. As the writing of the shellcode is based on C language which is relatively high in level, the code developing speed is fast; and the API is acquired dynamically based on the function written according to C language, so as to adopt to the *86 platform or the *64 platform automatically. Therefore, a developing personnel can maintain shellcodes of the *86 platform and the *64 platform in a unified manner; and the shellcodes are easy to develop and maintain, and are unified, while complex functions can be realized easily.