With the deeper research and application of quantum key distribution (QKD), the quality and generation rate of random numbers are facing greater challenges. In order to meet the use of random numbers in QKD system and in the scenarios with high requirements for key security, an experimental scheme for generating true random numbers based on vacuum fluctuations is presented. Compared with the 2 × 2 polarization beam splitter (BS) used in traditional solution, a single mode 1 × 2 BS is used in the proposed scheme to realize the transmission of optical path, which not noly saves device costs but also obtains a high random number generation rate. Under the action of 9.68 dBm light intensity, the signal-to-noise ratio of quantum noise to classical noise of 11.92 dB is obtained. The data collected through a 12 bits analog-to-digital converter is analyzed. The results show that both the classical noise and the vacuum shot noise are in accordance with Gaussian distribution, and the calculated minimum entropy is 9.92. The original data is subjected to Toeplitz post-processing, whose security can be proved according to information theory. Finally, the quantum random number generation with the rate of 7.6 Gbit /s is acheived, and it successfullly passes the NIST random number standard test, verifying the feasibility of the scheme.