Aiming at the problem that the current quantum random number generation technology can not meet the safety and high rate requirement in the communication field, we propose an experimental scheme based on measuring the vacuum fluctuations of the light field to produce quantum true random numbers in this paper. Different from the experimental schemes reported in the past, we theoretically analyze the influence of the gain of the local oscillator on the relative quantum entropy content of the original random numbers in the quantum orthogonal component measurement of quantum random number generation system. The quantum condition minimum entropy is used to quantify the randomness of the original random numbers under the worst case assumption that the classical noise is completely controlled by the eavesdropper. Based on the theoretical analysis, the vacuum noise fluctuations are experimentally amplified by relatively increasing the local oscillator intensity while controlling the electronic gain and the classical electronic noise. The minimum entropy content introduced by the quantum noise in the system is improved. At the same time, the vacuum quantum noise is broadband Gaussian white noise, which effectively increases the bandwidth of extractor frequency-band, as well as the utilization rate of quantum entropy source and the security of the quantum random number generation system while increasing the rate of quantum random number generation. The results show that the Toeplitz-hash extractor based on the security information theory is provable. The quantum random number generation of 6.7Gbit/s is realized. The three standard tests for random numbers of Nist, Diehard and TestU01-SmallCrush are used to verify the true randomness of the quantum random numbers generated in this scheme, which provides a new way to increase the rate of generation of vacuum quantum random number generators.