Businesses'' innovation investment is an important driving force to accelerate the implementation of innovation-driven development strategy. Taking the data of A-share listed companies from 2015 to 2020 as samples， we empirically examined the influence of customer concentration on businesses'' innovation investment mainly from the heterogeneity perspective. The results show that the relationship is in a positive U-shape， which means that as customer concentration increases， businesses'' innovation investment shows a pattern of first decreasing and then increasing. Heterogeneity analysis shows that the above relationship is more significant in non-state owned businesses and businesses of low industrial monopoly and low supply chain integration. The results of this paper can enrich the study on the factors influencing businesses'' innovation investment， and also guide businesses to adjust their customer relationship management and improve their innovation investment.