Based on a background to the mould job shop, this paper considers a two-stage flexible flow shop scheduling problem subject to release dates, where the first stage is made up of unrelated machines and tasks have group constraint. The objective is to find a schedule that minimizes makespan in that flexible flow shop environment. For this problem, a mathematic model is formulated. Because this problem is NP-hard, an improved Palmer-based heuristic (denoted by MPL) is proposed. Based on MPL, a new heuristic (denoted by IMPL) is developed. In order to test the efficiency of the two heuristics, sets of examples are designed. Compared to the MPL, the performance of IMPL is more superior.