At present, in the field of code protection technology research, traditional obfuscation methods have obvious obfuscation characteristics, and analysts can perform customized de-obfuscation processing based on these characteristics. For this reason, this study proposes a code protection technology based on code slice fusion. This technology slices the target code into code fragments according to grammatical rules at the source code level, and inserts the fragments into different positions of another program according to the execution order and grammatical rules. After repairing the function call process and the data relationship, the fusion code that can run the two code functions normally is formed. A comparative experiment for the fusion code is carried out from three perspectives, namely, resource overhead, code complexity impact, and code similarity. The test results demonstrate that the implicit code obfuscation technique based on code slice fusion can effectively obfuscate code semantics, change control flow characteristics, and has no obvious obfuscation characteristics. Therefore, fusion technology has obvious advantages in the ability to fight against multiple similarity comparison algorithms.