Aiming at the collaborative optimization problem of interval number reentrant hybrid flow shop scheduling and preventive maintenance (PM), an integrated scheduling model is constructed, which takes the interval makespan, total carbon emissions and total PM costs as the optimization objectives. For this problem characteristics, the Pareto relation of solution in interval sense is defined by designing the improved possibility calculation method. Besides, an improved discrete whale swarm algorithm is proposed, which designs a synchronous scheduling and maintenance strategy to realize the joint optimization of manufacturing and maintenance. Also, a distance calculation strategy between individuals to find the "nearest better individual", and an individual position movement strategy and a multi-neighbourhood search strategy are designed to effectively balance the global and local search in order to improve the convergence accuracy. Simulation results and statistical comparison with extensive experiments show the effectiveness and feasibility of the proposed algorithm for solving the collaborative optimization problem of interval number reentrant hybrid flow shop scheduling and preventive maintenance.