The Belt and Road Initiative (BRI) provides new opportunities and great space for China's outward foreign direct investment (OFDI) cooperation, as evidenced in 2018 when it financed US$15.64 billion in 56 countries along this burgeoning economic path, targeting Europe, Africa, and Asia as its hot spots. However, most of the countries along the Belt and Road are low-growth, middle-income, and developing economies, and their infrastructure, export trade, and other factors play an important role in the security and efficiency of OFDI. Therefore, this research selects 60 countries in Europe, Asia, and Africa as the objects and uses the common boundary SBM model to calculate the investment efficiency of 7 indicators from 2013 to 2017. The results show a significant regional gap in the efficiency of China's total foreign investment. The efficiency scores of European countries are generally better than those of Asian and African countries, while the technology gaps of countries in Asia and Europe are higher than that in Africa. The efficiencies of three major indicators, FDI, infrastructure development indicator (IDI), and export trade (ET), exhibit four types of distribution. Therefore, it is necessary to coordinate and optimise the proper investment layout, enhance China's investment quality in countries along the Belt and Road, strengthen exchanges and cooperation between think tanks, and promote further construction of BRI.