A Wireless Broadband Communication System has been made up based on OFDMA and AMC technologies. The system structure and working pattern is introduced, the OFDMA allocation model, the MIMO and AMC scheme are present, and the parameter such as transmitting power, receiver sensitivity, transmitting antenna gain and receiving antenna gain are designed. The system enables high quality wireless broadband communication. As a supplement with wired communication systems, the system could fulfill the requirement of recovery local communication rapidly when some accidents take place.