Increasing the substrate concentration can effectively reduce energy consumption and result in more economic benefits in the industrial production of maltose, but this process remarkably increases the viscosity, which has a negative effect on saccharification. To improve saccharification efficiency, pullulanase is usually employed. In the conventional process of maltose production, pullulanase is added at the same time with β-amylase or later, but this process seems inefficient when the substrate concentration is high. Herein, a novel method was introduced to enhance the maltose yield under high substrate concentration. The results indicated that the pullulanase pretreatment of highly concentrated maltodextrin solution for 2 h greatly affects the final conversion rate of β-amylase-catalyzed saccharification. The maltose yield reached 80.95 %, which is 11.8 % above the control value. Further examination confirmed that pullulanase pretreatment decreased the number of branch points of maltodextrin and resulted in a high content of oligosaccharides. These linear chains were suitable for β-amylase-catalyzed saccharification to produce maltose. This research offers a new effective and green strategy for starch sugar production.