Data transported through the control system of WLAN included: burst real-time data (BRD), periodical real-time date (PRD) and non-real-time data (NRD). Priority ranged from the high level to the low level and distinguished them by different inter frame space (IFS). BRD station sent RTS to reserve channel freeing SIFS and transmitted burst data after SIFS; PRD transported through AP polling; non-real-time data transport through CSMA/CA protocol at the stage of DCF. This paper presented the new solution(limited and polling backoff, LPB) to solve the conflict, set conflict threshold, adopted modified backoff algorithm of burst real-time data, improved the performance of real-time data and guaranteed the delay to keep the delay limited. The analysis and simulation show that the new protocol can promote the response of real-time data and make the delay limited.