Rising import diversification of manufacturing industry may increase its productivity. Firstly, this paper uses UNCOMTRADE data from 2001 to 2014 to measure 25 China's manufacturing industries' import diversification and it is found that overall import diversification of China's manufacturing declines and then rises, presenting periodic fluctuations. Differences in import diversification lie in different factor intensity industries, and the import diversification of capitalintensive industries is the highest while the import diversification of resourceintensive industries is the lowest. Then this paper holds that import diversification of manufacturing industry can improve its productivity which is reflected in labor productivity through three channels including horizontal competition effects, horizontal learning effects and vertical spillover effects. And it uses system GMM method to estimate the dynamic panel data, confirming that the rising import diversity of manufacturing industry can increase the labor productivity. But the effect also differs in different factor intensity industries. Import diversification increasing significantly promotes labor productivity of resourceintensive and laborintensive manufacturing industry, while the impact on the capitalintensive manufacturing is not significant.