Adhesive anchors are widely used as post-installed fasteners in civil engineering. A typical steel-to-concrete connection includes multiple anchors which are commonly subjected to combined moment and shear loading. Based on the assumption that all anchors take up shear load， a revised method is developed for the design of ductile anchors， which considers that only the row of most stressed anchors in the tension zone are needed to meet the elliptical interaction of tension and shear capacity requirement during the design process of anchorage group under combined shear and moment loading. The ultimate strength of post-installed fastenings should be controlled by the strength of anchor steel for the purpose of connection safety and full utilization of anchor capacity. For the objective of ductile design in anchor group， the ratio of shear span could be used as an evaluation parameter in the process of strength prediction. According to the theoretical analysis and results comparison， the ductile failure of anchor steel in post-installed fastenings can be guaranteed when the ratio of shear span is greater than 0.6 and other anchorage requirement is met. In the end， design proposals and construction specification of anchor group are given for practice.