Research highlights the role of the shareholding proportion of the largest shareholder (TOP1) in the relationship of top management team (TMT) heterogeneity and corporate innovation performance. The empirical study makes use of a panel smooth transition regression model (PSTR) to investigate the nonlinear relationship between top management team (TMT) heterogeneity and corporate innovation performance in listed companies of household appliance industry. Data from a sample of 18 China listed household appliance industry from 2004-2014 provides us with a good opportunity to explore empirical evidences for the relationship. Following this idea, we propose to detect innovation performance by focusing on the proportion of the largest shareholder. We reveal that as the shareholding proportion of the largest shareholder becomes different, a nonlinear transition is found in relationship between TMT heterogeneity and innovation performance. The result shows that the model is divided into low regime and high regime at the point of TOP1 = 0.3144. Since equity structure and equity concentration varies in different regimes, the influence of TMT heterogeneity on corporate innovation performance has nonlinear changes as well.