The topic of quantum cryptography has begun to draw increasing attention recently. The most important factor is that the quantum cryptography is based on the principle of quantum mechanics, so it is more secure than the classical one. In this paper, we introduce a plaintext-related image encryption system which employed the two-dimensional two-particle discrete-time quantum random walks (QRWs) to construct a novel pseudorandom number generator (PRNG) used to generate the secret code streams. And it includes two plaintext-unrelated diffusion operations and one plaintext-related confusion operation. Simulation results and security analysis demonstrate that the proposed encryption scheme has good performance with high-level security.