An optical quantum random number generator based on parity of the number of photons detected in the equal time intervals was proposed.Light emitted from a continuous wave laser diode is attenuated into discrete single-photon sequence.The single photon is detected by a single-photon avalanche photodiode module.Random bit is extracted by measuring the parity of number of photons detected in equal time interval.The random bit extraction circuit based on field programmable gate array was developed.The influences of the size of time interval and the performance parameters of single photon module on performance of the designed random number generator were analyzed.In order to achieve a random bit generator with small deviation and fast generation rate,a method of setting time interval automatically according to average counting rate was proposed.A random bit generation rate of 2 Mbit/s was obtained when the designed random number generator works on a counting rate of 20 Mcps and the equal time interval is set as 0.5 μs.The random bit sequences were tested by random number test program ENT and STS.The test results show that the generated random bit sequences fully meet the standards of true random numbers,and do not require post-processin