NAND flash memory is becoming more widely used in various computing systems due to improved cost effectiveness. This research is to design a cost effective solid state disk that can support high sequential-access performance, by constructing a multi-block interleaved structure. As a way of complementing the shortcomings of MLC (multi level cell) flash memory, a group of different interleaved modules is constructed to be selectively accessed depending on request sizes. MLC flash is used in this structure because of its low manufacturing cost per capacity, even though it has a slower transfer speed and lower life endurance than SLC (single level cell) flash. Our approach is to implement an optimized MLC bank interleaving structure for applications with a high potential of sequential locality. Simulation results show that the multi-interleaved structure with sequential locality can achieve around 13.6% and 6.2% improvement in terms of reading and writing performance, compared to any single interleaved conventional structure without block separation.