Innovation is an important factor for a company to maintain its competitive advantage， but why the company with good performance invests less in innovation. Based on the data of the listed subsidiaries from 2012 to 2019， exploring the factors that hinder technological innovation of the subsidiary from the perspective of agency theory， it finds that innovation input decreases when the performance of the subsidiary is good； and the tunneling behavior of the headquarters， related party transactions between companies within business groups and the agency behavior of senior executives are the influencing factors that hinder technological innovation of the good-performance subsidiaries. Further study explored how to restrain the agency behavior. The results show that the supervision impact of independent directors on the two kinds of agency behaviors of subsidiaries is not significant； institutional investors restrain the tunneling behavior of headquarters to the subsidiary with good performance； the external institutional environment weakens the agency behavior of senior executives in the good-performance subsidiaries. It reveals the internal influencing mechanism of low innovation investment in the good-performance subsidiaries from the perspective of agency behavior， and provides suggestions on how to restrain the agency problems of subsidiaries and reduce innovation resistance from the management level， company level and environment level.