This paper investigates the problem of multi-retailer joint replenishment for single product under uncertain demand. First, a joint replenishment EOQ model with shortage and demands represented by triangular fuzzy numbers is constructed to find the retailers' optimal triangular fuzzy ordering quantities and the coalitions' cycle lengths and the triangular fuzzy average costs. Second, we develop a simplified method based on our defined coalition size monotonicity-like conditions to calculate the triangular fuzzy proportional surplus division value for a special subclass of triangular fuzzy cooperative games. The triangular fuzzy proportional surplus division value can be obtained through computing the mean and the lower and upper limits by using the mean and the lower and upper limits of the relevant triangular fuzzy coalitions' values, respectively. Some important properties of the triangular fuzzy proportional surplus division value are proven. Finally, the proposed triangular fuzzy proportional surplus division value is used to allocate the triangular fuzzy average costs. The applicability and effectiveness of the proposed model and method are demonstrated with a numerical example. This paper may provide a new way and method for solving complex inventory management problems.