Abstract:  In order to reveal the effect of manufacturing practice between market orientation and operation performance, a research from the perspective of modularity was performed. Based on 204 valid samples, it was empirically examined that, customer orientation and competition orientation had significant positive effect on product modularity (β=0-21/0.20) but not on process modularity, and that product modularity had significant positive effect on process modularity (β=0-46), but it showed no significant impact on operating performance while process modularity demonstrated significant positive impact on operational performance (β=0-29). In addition, it was empirically tested that control variables of firm size and firm age had no significant effect on operation performance. The research indicates that modularity could be an effective manufacturing practice to improve operation performance when the firm implements market orientation strategy. However, difference between the mechanism of the product modularity and process modularity should be noticed.