A high speed random number generator based on digitizing bandwidth-enhanced chaotic laser signal is proposed and demonstrated. In order to remove the weak periodicity in optical feedback chaotic semiconductor laser signal, the optical feedback chaotic semiconductor laser is injected into another semiconductor laser to obtain a bandwidth-enhanced chaotic laser signal. The bandwidth-enhanced chaotic laser signal is converted using an 8-bit high speed analog-to-digital convertor to achieve generating multi bits by each sampling point. In order to remove the bias existing in original extracted random bits and improve the efficiency of random bit generation, fieldprogrammable gate array based secure hash algorithm 256 is proposed to extract random bit. Due to the use of 4-channel parallel processing technology, online random number generation rate of 2.94 Gbit/s is obtained and each sample could produce average 4.65 random bits. The obtained random numbers pass all the tests in random testing program of ENT and STS.