The invention provides a method for using a software protection device to store application codes so as to protect software. The invention stores parts of machine instructions or script languages of an executable program into the software protection device, the instructions or script languages are extracted dynamically from the software protection device during the program operation process and are executed on a PC, and the codes need not to be transplanted when the program codes are protected and the method is easy to be realized. Simultaneously, as the protected codes are executed on the PC, a plurality of sections of the codes in the program can be stored for protection without impact on the operation efficiency of the program and the protection intensity of software is enhanced. The invention provides an easy, efficiency and safe method for software protection.