This paper proposes a collision detection method for ERCP simulation. In the ERCP operation, doctor inserts the endoscope into the mouth then pass through an upper gastrointestinal tract to diagnose and treat disease in the bile duct and pancreatic duct. In the simulation of this procedure, it is important to resolve interference between the upper gastrointestinal model and the endoscope model to provide a realistic visual feedback. This paper proposes a collision detection method optimized to a lattice-based deformable model which is employed to compute deformation of the upper gastrointestinal model in real-time. This lattice-based collision detection method can reduce collision detection time without failure of collision detection.