Based on the unbalanced panel dataset including 78 listed companies in the Shanghai and Shenzhen motherboards, with 686 firm-year observations from 2000 to 2012 and by controlling the factors of firm size, firm age, capital expenditure, sales growth, industry average Q and so on, the paper adopt quantile regression model to conduct an empirical study on the relationship between corporate venture capital portfolio diversification (CVCPD) and corporate investor’s firm value (CIFV) as well as the moderating effect of organizational slack(OS). Some conclusions were drawn from the research: established companies make use of corporate venture capital to realize value creation only under the conditions that the corporate investor has had a certain level firm value, and there exists a U-shaped relationship between CVCPD and CIFV. Furthermore, the U-shaped relationship was moderated positively by the corporate investor’s OS. However, the different corporate investors’ firm value level the different moderating effects of the OS, so the different extreme points of CVCPD. So the incumbent firms should adopt different investment strategies in line with the level of OS and firm value.