This paper presents the pattern cutting and ligating loop simulation in the Virtual Basic Laparoscopic Skill Trainer (VBLaST©). In the simulation, the gauze, tubular foam, and ligating loop thread are modeled by the mass-spring method and constraint projection for the inextensible characteristics. Discrete simulation states defined based on the tool-object interaction types are utilized to efficiently and accurately manages the physics simulation, collision processing, and haptic feedback in real-time. An automated scoring system provides quantitative measurement for evaluation of trainees' skills. The simulation results show advanced visual realism and real-time performances.