With the recent improvements in cryptanalysis, more applications have started to use Advanced Encryption Standard (AES) instead of Data Encryption Standard (DES) to protect their information and security. However current implementations of AES algorithm suffer from huge CPU resource consumption and low throughput. The authors studied the technologies of GPU (Graphics Processing Unit) parallel computing and its optimized design for cryptography. Then, using CUDA functions for AES parallel encryption; they designed and implemented a fast data encryption system based on GPU. The tests proved that their approach accelerated the speed of AES encryption significantly.