Traditional means of performance measurement, however, are either based on few predefined factors that provide only a partial view of the system or limited to a single activity and thus ignore the interaction between activities. To address this problem, a modified model for data envelopment analysis with multi-activity networks is proposed for accounting firm in this paper. We assess 298 Taiwanese accounting firms with three parallel-connected activities having two series-connected processes and two share factors for their performance management. After evaluating the effectiveness of the model, our results show that Taiwanese accounting firms obtain great advantages in the service process and suggest that Taiwanese accounting firms should focus on firm production for human resource arrangement and training expense and labor cost shares.