Entangled state quantum detection is a new technology that combines quantum mechanics with information science and is applied in the field of target detection. It has the potential to break through traditional detection technologies in terms of sensitivity and anti-interference ability. In the field of radar detection, constant false alarm detection is a technology with important significance and application value. However, there is no research on the detection method of constant false alarm in the entangled state quantum detection system in the world. Aiming at this problem, this paper proposes a constant false alarm detection method for the entangled state quantum detection system. The proposed method adopts the system's real-time estimation of noise and adaptively adjusts the detection threshold, so that the entangled state quantum detection system always maintains a constant false alarm probability during the detection process. The simulation results show that the proposed constant false alarm detection method is correct and effective, and can realize the constant false alarm detection function of the entangled state quantum detection system. The proposed method effectively improve the flexibility and adaptability of the quantum detection system, and provides a solid theoretical foundation for the practicality and application of entangled state quantum detection technology.